典型登革热的热型是（）
A.回归热
B.稽留热
C.波状热
D.马鞍热
E.弛张热
参考答案：D
相同温度、相同物质量浓度的四种溶液：①CH3COONa、②NaHSO4、③NaCl、④Na2CO3按pH值由大到小的顺序排列，正确的是
A．④>①>③>②
B．①>④>③>②
C．①>②>③>④
D．④>③>①>②
It was _____ he came back from Africa that year _____ he met the girl he’d like to marry.
A．when; then
B．not until; that
C．only; when
D．not; until
