The retired professor, _____ in his new book in the past three years, hasn’t realized the decline in his health. 
#12131
A
involved
B
being involved
C
having involved
D
to be involved
推荐题目
We are waiting until the weather ________ a little.
#13368
A
takes up
B
picks up
C
turns up
D
makes up
The doctor told me to take the medicine_____.
#12998
A
every fourth hours
B
each fourth hour
C
each four hours
D
every four hours