A.It helps to keep the eyes moist. B.It helps the eyes absorb eye-drops. C.It improves a person's concentration. D.It prevents a buildup of chemicals in the eyes.
A.It B. B.It C. C.It D. D.It
【参考答案】
A 解析:本题是因果题。从When you blink... helps moisten your eyes.可......