Many provinces have been hit with smog. If _______ unsolved, the problem may lead to more serious results.
| A．having left | B．to leave | C．left | D．leaving |
The businessperson wanted to sell his goods fast; ______, he chose his partner with great care.
| A．therefore | B．otherwise |
| C．for | D．however |
Do you know the man____ is talking with Tom?
| A．which | B．who | C．whom | D．whose |
A dictionary is a book ______ gives the meanings of words.
| A．which | B．who | C．whom | D．whose |
The old town has narrow streets and small houses ________ are built close to each other.
| A．they | B．where | C．what | D．that |
Do you want a friend ______ you could tell everything to?
| A．which | B．whose |
| C．whom | D．he |