In the past few years, research has suggested that Vitamin D may increase the level of serotonin(血清素), one of the key nurotransmitters influencing our mood, and ________it helps to relieve mood disorders.
---What can I do for you?---Well,I’m afraid the box is heavy for you,but thank you all the same.
I was advised to arrange for insurance _____ I needed medical treatment.
--_____ of the population of the city _____workers? --About 60 percent.
Although he is considered a great writer, _____.
He advised the fanners to choose the best seed-heads,____ that had the best colour.