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1.        According to a study published by Dr. Myrna Weissman, only one percent of Americans born before 1905 had suffered major depression by the age of seventy-five; of those born since 1955, six percent had become depressed by age twenty-four.

(A) only one percent of Americans born before 1905 had suffered major depression by the age of seventy-five; of those born since 1955, six percent had become depressed by age twenty-four

(B) only one percent of Americans born before 1905 suffer major depression by the age of seventy-five; if they are born since 1955, six percent become depressed by age twenty-four

(C) of Americans born before 1905, only one percent of them have suffered major depression by age seventy-five, but six percent of those born since 1955 do by the age of twenty-four

(D) major depression is suffered by the age of seventy-five by only one percent of Americans born before 1905, and by age twenty-four by the six percent born since 1955（A）

(E) Americans born before 1905 suffer major depression by the age of seventy-five only one percent of the time, but six percent of those born since 1955 did so by age twenty-four

为什么要用过去完成时态呢？不是很懂哦。求人解答丫～～

C的“but”为什么不行呢？不是两个句子也可以理解比较么？

is A the right answer?

by the age of seventy-five, 理解这个短语就明白了。by有“到。。。时”的含义，是一个过程。

这里没有转折的句义，不能用but，记得以前有过很多讨论，MM发贴前先搜一下，可以节约很多时间。

不同意楼上

句子的意思是说到了70岁才开始suffer，而不是suffer到70岁结束

用过去完成时是因为,那些人从70岁开始到这个study公布，都在suffer

但要用过去完成的话，只能假设这个study的公布是个过去时

A.正解

B.suffer现在时，错

C.
            of Americans born before 1905, only one percent of them have ....重复，错

D.及其wordy，看都不看，排除！十几个by表达混乱

E.改变句子意思，不是只有1％的时间suffer，是只有1％的人suffer