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
 The boy is very fat _______too much food.
#48695
A
so
B
so of
C
because
D
because of
 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