Many English words have been___________over the centuries. The___________of form makes English easy to learn.

A. mistakes

C. changes

A. After the USA put the first human on the moon, Russia had already sent the first human into space.

B. Before the USA put the first human on the moon, Russia had already sent the first human into space.

D. The USA put the first human on the moon before Russia had already sent the first human into space.

A. The place has a microgravity environment where astronauts live and conduct research.

B. The place which astronauts live and conduct research has a microgravity environment.

C. The place where astronauts live and conduct research has a microgravity environment here.

D. The place where astronauts live and conduct research has a microgravity environment.

A. Ø – the

B. the – the

C. the – Ø

D. take