北京新航道致力于为广大考生提供托福培训以及托福考试资讯。近些年来，托福考试越演越烈，家长都希望送孩子出国深造，为了将来的发展和自身的锻炼。托福考试也几经变革，但是总也离不开听说读写几个部分。其中，词汇是基础，贯穿于始终，是一门语言的敲门砖，掌握好词汇是托福考试的步。为了地帮助考生记忆词汇，北京新航道小编为大家整理汇集了一些词汇练习题，正所谓实践出真知，希望大家在做题的过程中加强对词汇的理解和掌握。

　　217. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmic "rays" are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds) .

　　The word "constituents" is closest in meaning to which of following?

　　(A) relatives

　　(B) causes

　　(C) components

　　(D) targets

　　218. Its relative abundance never seems to varymuch. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nucleial ways remains about the same.

　　The word "vary" is closest in meaning to which of following?

　　(A) mean

　　(B) stretch

　　(C) change

　　(D) include

　　219. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent.

　　The word "calculated" is closest in meaning to which of following?

　　(A) ignored

　　(B) converted

　　(C) increased

　　(D) determined

　　220. By the time the universe was a few minutes old, helium production has effectively ceased.

　　The word "ceased" is closest in meaning to which of following?

　　(A) extended

　　(B) performed

　　(C) taken hold

　　(D) stopped

　　上面是几道词汇题，大家都会了么?其实词汇掌握并不难，通过做题是的方法。在语境中体会词汇的用法才能掌握的更牢靠。祝大家取得好成绩。

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