. _________ is known to all, good friends _________ happiness and value to life.
| A．It; add | B．As; add | C．It; add to | D．As; add to |
The roads are lined _____trees, which have been planted to hold _____the strong winds from the north.
| A．along; to | B．on; up |
| C．with; back | D．in; against |
He earned enough money to start his own business _____ offering guide services _____ tourists.
| A．by; to | B．with; at |
| C．on; for | D．through; with |
_____ the night, we did nothing but _____ there, waiting for him to come.
| A．All through; sit | B．All over; to sit |
| C．Whole; sitting | D．Throughout; sat |
_____ your help, we _____ complete the work in time.
| A．Thanks to; were able to | B．Thanks to; could |
| C．As; would | D．Because; had to |
I have a letter _____ to tell the headmaster that we need a room _____.
| A．to write; to live in | B．to be written; living in |
| C．to write; to live | D．written; to be lived in |