在4A+5B=4C+6D的反应中，已知34gA和80gB完全反应，生成了54gD，若已知C的相对分子质量为30，则A的相对分子质量为　 [ ]

A．68

B．34

C．32

D．17

If we take a close look at successful language learners, we may discover a few techniques (技巧) which makes language learning easier for them.
(16) , successful language learners are independent learners. They do not depend on (依赖) books or teachers; they (17) their own way to learn the language. They try to find the patterns and the rules for themselves, (18) waiting for the teacher to explain everything. They are good guessers who look for clues to form their (19) conclusions which are very different from others’.
Successful language learning is (20) learning. Therefore, successful learners do not wait for a chance to use the language; they (21) such a chance. They find people who speak the language and ask these people to correct them (22) they make mistakes. They will try anything to communicate. When communication is difficult, they can (23) information that is incomplete (不完整的). It is more important for them to learn to (24) in the language than to know the meaning of every word.
Finally, successful language learners are learners with a (25) in order to communicate with these people and learn from them. They want to learn a language because they are interested in the language and the people who speak it. It is necessary for them to learn the language.

Ⅱ. 完形填空

A．look for

B．care about

C．work out

D．write down