It is said that the number of forest parks in Guangdong _____ to more than 1,000 so far.
本题考查动词时态。根据so far 可知要用现在完成时，故答案为C。
As an exchange student,Alan _____ Qiqihar for one and a half years.
句意：作为一名交换生，艾伦在齐齐哈尔住了一年半了。表示“在某地居住了多长时间”要用have been in,故答案为B。
Tea is one of _____ drinks in the world.
本题考查含最高级的句式。句意：茶是世界上最受欢迎的饮品之一。根据“one of the + 形容词最高级+ 可数名词复数”的结构可知答案为D。