某无土栽培用的营养液，要求KCl、K2SO4和NH4Cl三种固体原料的物

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问题选择题

某无土栽培用的营养液，要求KCl、K₂SO₄和NH₄Cl三种固体原料的物质的量之比为1：4：8．若配制该营养液，取428gNH₄Cl，则需KCl和K₂SO₄的质量分别是（　　）

A．53.5g和214g

B．74.5g和348g

C．74.5g和696g

D．149g和696g

答案

答案：C

选择题

Walter offered us a lift when he was leaving the office, but our work ______, we didn’t accept the offer.

A．not being finished

B．having not been finished

C．had not been finished

D．not having finished

单项选择题

唐山地震后在30分钟以内抢救出来的人员成活率是（）

A、85%

B、60%

C、95%