Today Chinese is becoming more and more popular. It _____ in many schools around the world. [ ]

A. teaches

B. has taught

C. is taught

D. is teaching

下列四种情况，所得溶液质量为2g的是（　　）

①1g镁与1g盐酸反应

②室温下，1g饱和食盐水与1g水混合

③室温下，1g饱和食盐水与1g食盐混合

④1g氢氧化钠溶液与1g稀硫酸反应．

A．①②

B．①③

C．②④

D．①③④