He is trying to find a new way to（）a living. Which of the following is incorrect.

单项选择题Several languages are likely to die（）

A.out
B.down
C.off
D.of

单项选择题Heat causes the（）of gas.

A.growth
B.increase
C.expansion
D.extension

单项选择题He is（） at doing this kind of job.

A.imefficient
B.nonefficient
C.unefficient
D.inefficient

单项选择题Cycling is a good exercise.（）, it doesn't pollute the air.

A.Therefore
B.Moreover
C.But
D.However

单项选择题Speed limits should lead（） fewer deaths on the roads.

A.to
B.off
C.on
D.in