下列能保持氢气化学性质的是
A．H
B．H+
C．H2
D．2H
答案：C
分子是保持物质化学性质的最小粒子，所以能够保持氢气化学性质的是氢分子．
故选C
The scientist told the reporter that only after he went abroad ______ what his motherland meant to him. [ ]
A. he realized
B. did he realize
C. had he realized
D. he had realized
英国人汤姆的护照上贴有有效的我国J-1签证，可以判断他是（）。
A、常驻我国的记者
B、临时到我国采访的记者
C、到我国进修的学生
D、到我国旅游的旅客
