Many students didn’t realize the importance of study _______ they left school.
A low-carbon(低碳)lifestyle has an effectour daily life. More and more attention has been paid toenergies these days.
The teachers ________________ the office for a few minutes when we arrived.
——Would you mind my opening the window? ——__________.
—— He didn’t catch the train, did he? ——__________, though he was caught in the rain.
—— Is Jim at home by himself? —— No, there is another boy __________ with him.