Scientists say human activity contributes to climate change, but they do not agree on the rate_______ climate change may be developing.
A.with which | B.with that | C.at which | D.at that |
. It is difficult for us to learn a lesson in life __________ we’ve actually had that lesson.
A.until | B.after |
C.since | D.when |
.__________ he had not hurt his leg, John would have won the race.
A.If | B.Since |
C.Though | D.When |
.I won’t call you, __________ something unexpected happens.
A.unless | B.whether |
C.because | D.while |
. He was told that it would be at least three more months __________ he could recover and return to work.
A.when | B.before |
C.since | D.that |
.Most birds find it safe to sleep in the trees, but __________ they have eggs or young chicks, they don’t use a nest.
A.why | B.how |
C.unless | D.where |