病毒区别于其他微生物的主要特征是()A．只含有一种核酸 B．严格活细胞内寄生 C．对

在夜空中寻找除地球以外的七大行星，应在何处去找

A．黄道地球公转轨道附近

B．赤道附近

C．南北极上空

D．南北纬45°上空

Now the Chinese eat      as they actually need every day.

A．twice as much protein

B．twice protein as much

C．protein as twice much

D．protein twice as much

用98%的浓H₂SO₄（ρ=1.84g．cm^-3）配制1mol/L的稀硫酸100mL，按配制溶液时仪器的选用顺序排列，选择正确的是（　　）

①玻璃棒  ②胶头滴管   ③100mL容量瓶   ④托盘天平  ⑤50mL烧杯   ⑥10mL量筒   ⑦100mL量筒   ⑧移液管   ⑨滴定管．

A．⑥③⑧⑤①②

B．⑥⑤③①⑨②

C．④⑤③②①⑨

D．⑥⑤①③②

He ________ whether the articles exhibited at the back of the department store were for sale. [ ]

A. demanded    

B. decided

C. required    

D. requested

污水装置各采样点的PH值和悬浮物的控制指标？