At _______, photography is a chemical process, during which a light-sensitive material is altered when exposed to light.

Mr. Brown had the report ______ as soon as he finished ______ it.

The mother was afraid to let the boy ______ the tree.

They ______ a tip if the service is poor.

______ he was chosen and trained as a professional swimmer.

For the first time ______, man was able to set foot on the moon.

______ coming of the Space Age, a new dimension has been added to the study of the planets.

The salary of a skilled worker is much higher ______.

Though her father never approved of ______ to drama school, she became a well-known actress.

Not until a monkey is several years old ______ to exhibit signs of independence from its
mother.

A person＇s blood flows through a pipeline of vessels that, end to end, would stretch more than ______ half times around the Earth at the equator.