我国法定的职业肿瘤是（）。

A.紫外线所致皮肤癌

B.电离辐射所致白血病

C.氯甲醚所致肺癌

D.苯胺所致膀胱癌

E.镍和镍化合物所致肺癌

• (A) 条件(1)充分，但条件(2)不充分．
• (B) 条件(2)充分，但条件(1)不充分．
• (C) 条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．
• (D) 条件(1)充分，条件(2)也充分．
• (E) 条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．

There are 105 students taking history and/or mathematics. How many students are taking only mathematics
(1) Thirty students are taking history only.
(2) Fifty students are taking both history and mathematics.