根据我国《保险法》的规定，在人身保险合同中，被保险人或者投保人可以变更受益人并书面通知保险人。投保人变更受益人时须经被保险人同意。
参考答案：对
— You seem to know much about the city.
— That's true. I _____ it three times. [ ]
A. visited
B. had visited
C. have visited
D. will visit
图中三位同学正在讨论某一物质，他们所描述的物质是
A．HCl
B．S02
C．CO2
D．Cl2
