从6名女生、4名男生中，按性别采取分层抽样的方法抽取5名学生组成课外小组，则不同

—The bell rang for a long time. Why not answer it?

—I ______ taking a bath on the second floor. [ ]

A. is

B. was

C. were

D. are

You should be more careful,  _______ you might meet with some accident.

A．meanwhile

B．otherwise

C．although

D．however

结核结节主要由哪种细胞组成（）。

A.上皮样细胞及Langhans巨细胞

B.淋巴细胞

C.Langhans巨细胞

D.成纤维细胞

E.浆细胞

膀胱肿瘤中最常见的为下列哪种（）

A.移行细胞癌

B.腺癌

C.鳞状细胞癌

D.横纹肌肉瘤

E.嗜铬细胞瘤

新时期社会矛盾的特点是什么？