腺源性感染最常见于
A．咽旁间隙
B．翼下颌间隙
C．下颌下间隙
D．舌下间隙
E．颞下间隙
参考答案：C
解析：腺源性感染较牙源性感染少见。
Our flight to Guangzhou was ________by a bad fog and we had to stay much longer in the hotel than we had expected.
A．delayed
B．adjourned
C．cancelled
D．preserved
一般来说，恩格尔系数在（ ）时，人们开始逐步注重农产品质量安全。
A．25%以下
B．25%～40%
C．40%～50%
D．50%以上
