We must________the weather into consideration first when climbing mountains.[ ]

We have made good preparations for Sarah’s birthday, but if she ________ late to the party, it would ruin the surprise for her.

The Mekong River Commission has found no evidence______ the dams on the upper reaches have an influence on the water flowdownstream

Exploring the polar regions is a _______ issue because it may destroy the ecological environment there.[ ]

In drawing up the plan, they went to the library to _____ many books.[ ]