题目

I bought a pet dog yesterday, but I don't know how to ______ it.     A. look for        B. look after           C. look at                  D. look over  答案：B下列图示实验操作中正确的是A．向试管中滴加液体B．给试管中液体加热C．称量一定质量的食盐D．检查装置的气密性