You shouldn’t drive        fast.It’s dangerous.

The new group of students is better-behaved than the other group who stayed here ________. 

-- You seem to be burning yourself out with so much work!-- ______. I'm dying for a thorough rest and a good workout.

It’s reported that global warming is heating the planet twice as quickly as _____ feared.

We often say that something is “as light as air”, but air is＿＿＿light.