按照美国FDA药物毒性妊娠分级标准，左旋甲状腺素钠属于（） A.A级 B.B级 C.

如果⊙O的直径为10cm，弦AB=6cm，那么圆心O到弦AB的距离为（       ）cm。

— Is there a bookstore near here?

— ______. Look! It's next to the school. [ ]

A. Yes, there is

B. No, there isn't

C. Yes, it is

D. No, it isn't

Tom got a full mark in the English final exam, so his parents were very _____.[ ]

A. impressed

B. impress

C. impressing

D. to impress

既可清热燥湿，又善清心、胃实热的中药是（）

A.龙胆

B.黄芩

C.苦参

D.黄柏

E.黄连

什么是复式记账法其特点有哪些