Sound travels ______ air ______ a speed of about 340 metres per second.
#47987
A
over; in
B
through; at
C
by; at
D
through; over
推荐题目
Tom has much difficulty _____Chinese so he often asks me ______help.
#51113
A
understanding; for
B
understanding; of
C
to understand; for
D
to understand; for
The doctor gave me some medicine____my cough and told me to take it _____a day.
#46893
A
of; twice
B
for;three
C
for;twice
D
to;twice
