These big rocks ( ) for military trucks to pass.

These big rocks ( ) for military trucks to pass.
A、have cleared away
B、have to be cleared away
C、have to clear away
D、have been cleared away
【正确答案】：B
【题目解析】：have to be done，情态动词后接被动形式，clear away 清除，清理。句子含义为：这些大岩石必须清除掉以便让军车通过。