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.
| A．that | B．where | C．what | D．which |
---How did you find the book?
---.Great, and also the book review says Shakespeare ________ all his characters in the play vivid and alive.
| A．made | B．makes | C．had made | D．has made |
It makes his life quite differenthe has received higher education abroad.
| A．that | B．which | C．what | D．how |
Knowing office rules 
— whether _______ or not—is critical, particular for young job seekers.
| A．written | B．writing | C．being written | D．having been written |
_______Dalian with Tianjin, and you will find that Dalian is a better place to live in.
| A．To compare | B．Comparing | C．Compare | D．Compared |
---What _______do you have with that businessman?
--- He is my regular customer.
| A．connection | B．relation | C．effect | D．influence |