There are still many problems ______ before we are ready for a long stay on the Moon.

The engineer buries himself in work all day long and has no time for some outdoor activities, __________ he has the interest.

Again and again the doctor_______ the crying baby girl, but he couldn’t find out what was wrong with her.

Take some time to _______ your successes and failures

下列各句中，表达得体的一句是( )