A
In order to know a foreign language thoroughly(完全地), four things are necessary. First, we must understand the language when we hear it spoken. Secondly, we must be able to speak it ourselves, correctly with confidence and without hesitation(犹豫). Thirdly, we must be able to write it. We must be able to make sentences that are correct in grammar.
There is no short way to succeed in language learning. A good memory is a great help, but it is not enough only to memorize the rules from a grammar book. It is no much use learning by heart long lists of words and their meanings, studying the dictionary and so on. We must learn by using the language. If we are pleased with a few rules we have memorized, we are not really learning the language. We must “Learn through use”. Practice is important. We must practice speaking and writing the language whenever we can.
小题1:The most important things to learn a foreign language are_______.
A．understanding and speaking
B．hearing, speaking, reading and writing
C．writing and understanding
D．memorizing and listening小题2:One can never learn a foreign language well only by_______.
A．much practice
B．studying the dictionary
C．learning through use
D．using the language小题3:“Learn through use” means_______.
A．we use a language in order to learn it
B．we learn a foreign language in order to use it
C．we can learn a language well while we are using it
D．both B and C
cm；它的体积为V=2x•x•（
）=
，（其中0＜x＜
）；对V求导，并令V′（x）=0，得
=0，解得x=0，或x=1；当0＜x＜1时，函数V（x）单调递增，当1＜x＜