下面哪个目录存放的是从后台同步到前台的ZDB文件（）.
A.DATA1
B.FTPDATA
C.VER
D.RELEVER
参考答案：A
31. Stronger and more lasting memories are likely to be formed ________a person is relaxed.
A．where
B．unless
C．when
D．Although
天然气的燃点是（）。
A.100℃
B.250℃
C.650℃
