It is human activities on the earth that are to _______ global warming.
---How was Mary’s performance?---Oh, pretty good. I was quite __.
An idea came to him ___ he might do the experiment in another way.
It is so wet there that the trees are extremely tall, some ________ over 90 metres.
Rather than ___ on a crowded bus, Tom always prefers __ a bicycle.
Perseverance is a kind of quality --- and that’s ________ it takes to do anything well.