The system is based _______ a network of metal pipes.
A. in
B. on
C. under
D. above
Air pumps are involved, but their role is limited _______ reducing resistance _______ the capsules' movement in the pipes.
A. to...to...
B. for...for
C. with...with
D. with...for
Capsules _______ up to 50 kg of goods could travel at 1500kph.
A. carry
B. carried
C. carrying
D. carries
You can wear _______ jeans in a few hours.
A. a
B. an
C. a pair
D. a pair of