设函数z=ln(1+xy)，则dz=______

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问题填空题

答案

参考答案：[*]

解析：[提示] 对x(或y)求导时，y(或x)应视为常数．用一元函数求导公式求出[*]代入dz即可．

选择题

The director couldn't figure out _______ made his assistant spend so much time in doing the survey. [ ]

A. what it was that

B. why it was that

C. how that was

D. what was it

单项选择题

哪个国际公约首次确立了“不得以保守银行秘密为由”拒绝司法协助义务的原则？（）

A、《联合国禁止非法贩运麻醉药品和精神药物公约》

B、《联合国打击跨国有组织犯罪公约》

C、《联合国制止向恐怖主义提供资助的国际公约》

D、《联合国 * * 败公约》