The flu is believed ________ by viruses that like to reproduce in the cell inside the human nose and throat.
#89170
A
causing
B
being caused
C
to be caused
D
to have caused
推荐题目
Every minute is made full _________ of ________ our lessons well.
#90654
A
use; studying
B
usage; studying
C
use; to study
D
usage; to study
He left his homeland, _________ never _________ back again.  
#95677
A
determined; to come
B
being determined; to come
C
determined; coming
D
determining; coming
When _______ to our school, the new study methods are popular with all the students.
#98455
A
to introduce
B
introduced
C
introducing
D
to be introduced