By the time Jack returned home from England, his son from college.
| A．graduated | B．has graduated | C．had been | D．had graduated |
_______ all these people have in common is ________ they have succeeded.
| A．What; that | B．That; what | C．That; that | D．What; what |
A fire _______ in the lower story during the midnight and soon the whole building was in flames.
| A．was breaking out | B．was broken out | C．broke out | D．break out |
Mary wanted to travel around the world all by herself, but her parents did not _______ her to do so.
| A．forbid | B．permit | C．follow | D．ask |
Good technique in medicine means less pain and fewer deaths and, ______ it’s our duty to master it.
| A．naturally | B．therefore | C．particularly | D．similarly |
In the group discussion, they thought up three different __________to solving the environmental problem.
| A．approaches | B．means | C．ways | D．methods |