.It was the 19th century heat was considered to be a form of energy.A. not until; thatB.

问题补充：

.

It was the 19th century heat was considered to be a form of energy.

A. not until; that

B. until; that

C. not until; when

D. until; when

答案：

(答案→)A. not until; that

B. until; that

C. not until; when

D. until; when

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