I usually spend an hour a day ________ my English.
A. study
B. to study
C. studying
D. studied
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If one smokes too heavily, he is ________ the risk of having lung cancer.
A. at
B. in
C. on
D. with
Not having breakfast will have a bad ________ on your health.
A. affect
B. effect
C. effective
D. affective
Mr. Smith comes to our store every day. He is our ________ customer.
A. frequent
B. busy
C. regular
D. usual
We have no money to buy a house, not to mention _________ a cottage.
A. buy
B. to buy
C. buying
D. bought