The black box is a necessary device on an airplane, which records its speed, direction and whether everything on the airplane______ normally. 
#102293
A
will function
B
functioned
C
is functioning
D
has functioned
推荐题目
Hearing his words, she left rather than _________ behind.
#103220
A
stay
B
stayed
C
to stay
D
staying
Great changes _____ in this city over the past five years.
#100896
A
tookplace
B
havetakenplace
C
weretakenplace
D
havebeentakenplace
 I used to drink a lot of tea but these days I _____ coffee.
#100930
A
preferred
B
prefer
C
have preferred
D
am preferring