234. After the 1911 Revolution, China began to use the Gregorian calendar (solar calendar) and at the same we have also used the lunar calendar(阴历) in which a leap year (闰年)______ every four years.
The strange man asked me to hand the letter to _____ I met in the police station, saying it was very important.
He told us whether _____ a picnic was still under discussion.
The computer was used in teaching. As a result, not only _____, but students became more interested in the lessons.
Please do me a favor —_____ my friend Mr. Smith to Youth Theater at 7:30 tonight.
You and I could hardly work together, _____?