The plan for the new design occurred to Mr. Smith______on his work recently.
| A．while concentrated | B．while concentrating |
| C．while he concentrated | D．while concentrating himself |
She now has to return home to have a long-time rest at her young age, because her health _____ under the great pressure of work.
| A．broke away | B．broke up |
| C．broke down | D．broke off |
________ stopping polluting the earth ________ hope to live in a better environment.
| A．Only to; we can | B．Only to; can we |
| C．Only by; can we | D．Only by; we can |
His friends were ___________and encouraged him to publish his ideas, but Copernicus was cautious.
| A．technical | B．official |
| C．educated | D．enthusiastic |
Our school was ________ in 1925 and has a history of more than 80 years.
| A．set up | B．set off |
| C．set out | D．found |
Our class _______ 55 students at that time.
| A．consisted of | B．consists of |
| C．made up of | D．was consisting of |