【单选题】We must derive hydrogen from renewable sources with a view to a pure hydrogen economy.
【单选题】在进行含水率测试时,土中水的质量一般不包括( )的质量。
【单选题】______, he can now only watch it on TV at home. (1998年考试真题)
A.
Obtaining not a ticket for the match
B.
Not obtaining a ticket for the match
C.
Not having obtained a ticket for the match
D.
Not obtained a ticket for the match
【简答题】We must derive hydrogen from __________________ with a view to a pure hydrogen, economy.