A.at danger
B.at risk
C.on edge
D.on the verge

A.admit
B.realize
C.recognize
D.find

A.The mission of the first working snakebot
B.Similarities between snakes and robots
C.How snakebots were invented
D.What a snakebot looks like and can do

A.The mission of the first working snakebot
B.Similarities between snakes and robots
C.How snakebots were invented
D.What a snakebot looks like and can do

A.Wheels
B.these things
C.regular robots
D.snakebots

A.appreciate
B.disapprove
C.admire
D.criticize

A.They can move freely.
B.They have many modules.
C.They will be made of plastic.
D.They can fly.

A.If it fell into a hole
B.If its head came off
C.If all its modules were broken
D.If its tail were broken

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.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