该地气温年较差（最高月平均气温与最低月平均气温的差）约为
A、5°C
B、10°C
C、15°C
D、30°C
答案：D
—Doctor, ____________should I take this medicine?
—Twice a day.
A. what time B. how much C. how often
“恶性骨肿瘤”最常见的转移的部位是（）
A.脑
B.骨骼
C.肺
D.脊椎
E.肝脏
