Vitamin D helps our bodies make a special chemical，and this special chemical，
__________，affects our brains，making us feel happy.
| A．in turn | B．in particular | C．in advance | D．in short |
How long have you ________ in the army?
| A．joined | B．come | C．stayed | D．served |
—Why did Tony leave our company?
—He was________ a better job at Haier.
| A．provided | B．offered |
| C．protected | D．owned |
________that you come here earlier tomorrow or you'll be in trouble.
| A．Be sure of | B．Make sure |
| C．It's sure | D．Make sure of |
Shut the window，________ it'll get too cold in here.
| A．but | B．so | C．however | D．otherwise |
I was so careless in the exam.________，I made so many mistakes.
| A．In this way | B．In other words |
| C．As a result of | D．As a result |