We had to wait one and half hours _________ we had already booked a table.
A. since B. although C. until before
21. In recent years _____ global warming is becoming ____concern for people all over the world.
| A．the; the | B．/; a | C．/; / | D．the; / |
Nowadays people have to pass various tests for professional __________ so that they can be qualified for a well-paid job.
| A．certificates | B．permission | C．admission | D．Perseverance |
There is an obvious __________ between the cultures of the West and East.
| A．content | B．contrast | C．contract | D．Contact |
We have strong __________ for believing that the mine accident in Heilongjiang was due to the poor management.
| A．grounds | B．reason | C．cause | D．Purpose |
I’m terribly sorry to turn you down this time, but I promise I will ________ to you next time.
| A．pick it up | B．make it up | C．turn it up | D．set it up |