31. In the past few years, research has suggested that Vitamin D may increase the level of serotonin（血清素）, one of the key neurotransmitters influencing our mood, and ________it helps to relieve mood disorders.
| A．that | B．where | C．what | D．Which |
I will treasure the encounter with the famous director who may ______my life.
| A．remark | B．accelerate | C．transform | D．contribute |
I always leave things about my son up to himself ______his decision is wrong, for I think he can learn more from failure.
| A．in case | B．even if | C．unless | D．until |
The passage was very difficult, so in order to ______what the writer really wanted to convey, I read it many times.
| A．give out | B．make out | C．make up | D．give away |
--- Mr. Brown is an actor and most of his children take up jobs related to show business.
--- ______, I guess. Ha! Ha!
| A．It runs in the family | B．You didn’t get the point |
| C．No one knows for sure | D．They are fond of their father |
It is said that a reliable treatment for the disease will be applied at least two or three months away and still it ______on animals.
| A．is testing | B．has tested | C．is being tested | D．has been tested |