Look! He’s running so fast!— Hard to _____ his legs were once broken. [ ]

Those who can achieve high grades in class tend to be weak in handling some practical problems, ________ is often the case.

_________ it rain tomorrow, we would have to _________ the spring outing.

下列各句中，没有语病的一句是（）

They _____ on the program for almost oneweek before I joined them, and now we _____ it as no good results have comeout.