_____ the loss of such a valuable jewel, Rachel's mother hires a famous detective _____ the thief.

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A．Troubled by; investigating

B．To trouble; to investigate

C．Troubling; investigating

D．Troubled by; to investigate

－________ are you trying to prove to the police?

－Where I was last night.

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I have no doubt ________ he'll turn up tonight.

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________ in the rain, he was wet to the skin.

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I could do nothing but _____ that I didn't know.

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A．to pretend　　　　　　B．pretend

C．pretended　　　　　　D．pretending

The wind direction is the direction ________ the wind blows.

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--Do you know Uncle Tom is crazy about gardening?

--Sure. He _____ his flowers in the garden now.

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A．may be watering　　　　B．must be watering

C．could look after　　　　D．ought to watch

--Why? Tom, your shirt is so dirty!

--Mum, I _____ my storeroom downstairs.

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A．cleaned　　　　　B．have cleaned

C．was cleaning　　 D．have been cleaning

One of his great inventions was ________ valued at the world scientific conference.

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－Mary looks sad. Did you tell her about the accident?

－Yes, but I ________ her later.

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