Some scientists believe that it won’t be long _______ robots are widely used in all walks of life．
| A．since | B．after | C．before | D．until |
_________ is known to us all that the earth is smaller than the sun.
| A．It | B．What | C．As | D．which |
Unreasonable ________, it turned out to be effective．
| A．though sounded the plan | B．though the plan sounded |
| C．the plan sounded though | D．sounded the plan though |
Due to bad weather we have to put ___ off until next week to go camping in the mountains．
| A．it | B．that | C．one | D．this |
—Do you know how to start the machine?
—________．I’m a green hand．
| A．Not a clue | B．Exactly | C．By all means | D．Just so-so |
We are a team so we must assist one another _____ completing the task．
| A．with | B．to | C．at | D．in |