This circuit is similar in operation to the circuit of Fig.1-10.

What kind of planet might NOT support life？

A．Most of the planets of the stars.

B．Stars similar to our sun.

C．Planets similar to the earth.

D．Planets with proper conditions.

Studies of marriage relationships indicate that ______.

A．opposites get on better than similar personalities

B．exactly the same bases for success apply for ordinary friendships

C．it is first of all necessary to limit prospective partners to people from similar back- grounds

D．the most successful are those between people who are alike but not exactly the same

What can be inferred from the latest survey？

A．Hospital teaching across the country is similar.

B．Children are better off without hospital teachers.

C．Only one-fourth of the hospitals have full-time teachers.

D．All hospitals surveyed offer special treatment to children.

【简答题】In the circuit

A circuit breaker differs from a fuse in that a circuit breaker ______.

A.melts and must be replaced

B.is enclosed in a tube of insulating material with metal ferrules(环) at each end

C.gives no visual indication of having opened the circuit

D.trips to break the circuit and may be reset