She devoted herself _____ to her research and it earned her a good reputation (名声) in her field [ ]

下列各句中，加点的成语使用正确的一项是

She was very hardworking ________he was very lazy.As a result，she passed the examination，but hefailed.[ ]

I think that ____ very difficult to learn.

MrsWhiteshowed her students some pictures _____ in Paris