题干
— How old is Mary?
— She is having her______ birthday this weekend.
A：four
B：the four
C：fourth
D：the fourth
答案(点此获取答案解析）
C
— How old is Mary?
— She is having her______ birthday this weekend.
A：four
B：the four
C：fourth
D：the fourth
量（1~2mL）低浓度（1×10-4mol/L）的酸性高锰酸钾溶液中。据此，下列说法正确的是
2C（g），△H <0，达平衡后，将气体混和物的温度降低，下列叙述中正确的是（ ）