单项选择题

A new technique（）, the yields as a whole increase by 20 percent.

A．working out
B．having been worked out
C．having worked out
D．to have been worked out

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单项选择题

Why did the author begin to doubt himself after the first year of his writing career（）

A．He wasn’t able to produce a single book.
B．He hadn’t seen a change for little barter.
C．He wasn’t able to have a rest for a whole year.
D．He found his dream would never come tru

单项选择题

The selection of medical professionals are currently based on（）

A．candidates’ sensitivity
B．academic achievements
C．competitive spirit
D．surer values