Look _____, Li Ming! [ ]
A. on
B. at
C. out
C
She stepped into the bedroom quietly _____she might wake up her roommates.
A.for fear that
B.so long as
C.on condition that
D.in order that
空心毛细管色谱柱气相色谱法的主要分离原理是()。
A.吸附
B.分配
C.离子交换
D.体积排阻