The flight to Beijing was canceled ________ the heavy snow．
A.asB.for thatC.becauseD.because of在线课程D
解析：
as，for that，because都用于引导原因状语从句，但because of无此用法，它后面只跟名词或代词．根据题目，这里给出的是一个名词，应该用because of．