Many parts of this car ________ in less developed countries, like Thailand.
A. produce
B. produced
C. are produced
D. was produced
Passengers must not leave their seats ________ the plane comes to a full stop.
A. until
B. since
C. if
D. because
Listen! Someone ________ at the door. Please go and answer it.
A. knocks
B. is knocking
C. has knocked
D. was knocking
More than six million guests ________ Shanghai Disneyland Park since last June.
A. visit
B. visited
C. were visiting
D. have visited
Taobao shop owners are busy ________ clothes for their online customers.
A. pack
B. to pack
C. packing
D. to packing
Something must be done to stop air pollution, ________ we will have no fresh air.
A. or
B. for
C. but
D. so
