A.The supply of oil is unpredictable
B.They are unwilling to sell their oil any more
C.They are not producing as much oil as they used to
D.Global warming more severe here than in other countries

A.It can reduce the amount of energy needed to power appliances.
B.It can tell them how much energy each appliance is using.
C.It can allow them to turn appliances on and off when they are not at home.
D.It can reduce their electricity bills.

A.They can't be used at off-peak times.
B.They do not provide much energy.
C.They always cause system failure and blackouts.
D.They do not supply a continuous flow of energy.

A.invite
B.promise
C.divide
D.attract

A.
B.
C.
D.

A.Constructed hundreds of years ago
B.It was constructed hundreds of years ago
C.Constructing hundreds of years ago
D.To have constructed hundreds of years ago

A.piles
B.sheets
C.pieces
D.packs

A.with
B.on
C.by
D.from

A.kept pace with
B.taken into account
C.taken care of
D.made room for

A.fruit
B.seed
C.stem
D.root