Your father is very strict with you.____. He never lets off a single mistake ofours.

The Shanghai Expo has had a major impactupon China. It is the first World Expo _________ in a developing country in theevent’s 159-year history.

The tour was fantastic in general, our car broke down on the way back

You should get down to your study from now on.Please________what is of great importance for your future development . [ ]

下列各句中画线成语的使用，不正确的一项是（ ）