????Facebook在去年二月推出最新廣告策略時還試圖為此構思了新的語言。通過向Facebook付費，廣告客戶可以在Facebook用戶的新聞推送服務中突出顯示“廣告軟文”（Sponsored Stories）。具體來說，只有發布的消息來自用戶已經關注的的好友或企業發布時，用戶才會看到這些廣告軟文。聽起來不錯，但廣告軟文的效用還遠未得到實踐檢驗。事實上，一些品牌甚至已經開始全盤質疑在Facebook上打廣告的價值。去年花費1,000萬美元在Facebook上做廣告的通用汽車（GM）已經決定停止在該平臺上打廣告，因為該公司的營銷經理們沒有看到他們所期望的廣告效應。谷歌誤打誤撞收獲了搜索營銷的利器，而Facebook還沒有找到自己的法寶。

第二：移動

????Facebook用戶轉投移動設備的速度已經超過該社交網絡能夠自如應付的水平。據互聯網信息服務提供商康姆斯科（Comscore）稱，目前，Facebook美國用戶通過智能手機和平板電腦等移動設備使用Facebook服務的時間約為7.4小時/月，高于通過臺式機登錄該網站的時間（約6.5小時/月）。

????這對該公司構成了兩大挑戰。首先，由于手機屏幕較小，Facebook用戶看到的廣告數量下降。這種令人不安的趨勢對Facebook的一些最重要的廣告市場造成了異常嚴重的沖擊。Facebook在最近提交給監管部門的文件中稱，這種轉變趨勢在美國、巴西和印度等地發展得最快。

????其次，即便Facebook能夠拿出解決方案，提供更多更好的移動廣告，該公司在移動策略上仍然落后于競爭對手。風靡市場的智能手機搭載的仍然是蘋果公司（Apple）和谷歌的操作系統軟件。隨著時間的推移，谷歌有可能實現自由社交平臺Google+與其安卓手機和平板電腦之間超越Facebook的無縫集成，從而在贏得消費者方面獲得優勢。Google+是Facebook的競爭對手。在過去的幾年中，扎克伯格曾試圖與蘋果結成更緊密的關系。據知情人士稱，Facebook與蘋果公司已舉行多輪磋商。但雙方還未能找到一個令人信服的方式進行合作；與此同時，蘋果公司沒有將Facebook集成至其移動軟件，而是選擇了Twitter。

????為了與競爭對手抗衡，Facebook一直在大舉收購移動資產。最值得注意的是，Facebook最近同意以10億美元收購照片共享應用開發商Instagram。Facebook將因此獲得一個擁有大量用戶的高增長產品，以及具有豐富手持設備設計經驗的優秀程序員團隊，后者或許更為重要。據最近監管機構備案，這筆交易預計要到今年晚些時候才能完成。

第三：中國

????我們不妨把中國稱作Facebook的黑洞：雖然Facebook貴為世界上最大的社交網絡，但截至目前它還沒有在中國開展業務。中國約有5億網民，用數量來衡量，是世界最大的互聯網市場。在中國，約有一半網民是本土社交網絡的活躍用戶。對于Facebook來說，雖然中國是一個巨大的、有利可圖的潛在市場，但是眼下可能仍然難以把握。

????Facebook attempted to coin new language for this when it launched its latest advertising strategy last February. Advertisers can pay Facebook to highlight "sponsored stories" in users' Newsfeeds. The idea is that users will only see these sponsored stories when they are posted by a friend or a business with which they've already chosen to connect. It sounds great, but the effectiveness of sponsored stories is far from proven. In fact, some brands are questioning the value of advertising on Facebook altogether. GM (GM), which last year spent $10 million with Facebook, decided to stop advertising on the platform because the company's marketing executives weren't seeing the impact they desired. Unlike Google, which stumbled on a magic formula with search marketing, Facebook has yet to find its silver bullet.

No. 2 Mobile

????Facebook's users are decamping to mobile devices faster than the social network can keep up. American Facebookers who use the service on both their desktops and on mobile apps are spending more time on their smartphones and tablets -- about 7.4 hours each month, according to Comscore (SCOR) -- than on the website itself -- about 6.5 hours each month.

????This poses two significant challenges for the company. First, mobile screens are small so Facebook users see fewer ads. This unsettling trend is disproportionately impacting some of Facebook's most important advertising markets. In recent regulatory filings, Facebook said the shift is happening fastest in places like the United States, Brazil and India.

????Second, even if Facebook can figure out how to serve up more and better mobile ads, the company lags behind its rivals on mobile strategy. Apple (AAPL) and Google make the operating software for the most popular smartphones on the market. It's possible that over time, Google could integrate its Facebook competitor, Google+, into its Android phones and tablets more seamlessly than Facebook, giving it an advantage with consumers. In the last couple years, Zuckerberg has attempted to forge closer ties with Apple. The companies have held multiple rounds of discussions, according to people with knowledge of the talks. But they have yet to find a compelling way to collaborate, and in the meantime, Apple has chosen to integrate Twitter, rather than Facebook, into its mobile software.

????To combat its rivals, Facebook has moved aggressively to acquire mobile assets. Most notably, Facebook recently agreed to purchase the photo-sharing app Instagram for $1 billion. The company will get a fast-growing product with tons of users and -- perhaps more importantly -- a pool of talented programmers experienced in designing for handheld devices. The sale isn't expected to close, according to recent regulatory filings, until later this year.

No. 3 China

????Call it Facebook's black hole: The world's biggest social network, as of now, has no presence in China. With some 500 million people online, China is the world's largest Internet market by number of users. About half of those users are active on locally grown social networks. It's a vast and potentially lucrative market for Facebook, but for the time being it's likely to remain elusive.