平行线之间的垂线只有一条.______.(判断对错)
由分析可知:平行线之间的垂线有无数条;
故答案为:×.
尿常规分析标本必须在多长时间内完成检验().
A.2h
B.5h
C.10h
D.16h
E.24h
If Pat bought a tennis shirt with matching shorts, what was the cost of the shirt ?() (1)The total cost of the shirt and shorts was $20. (2)The ratio of the cost of the shirt to the cost of the shorts was 2:3.
A.条件(1)充分,但条件(2)不充分.
B.条件(2)充分,但条件(1)不充分.
C.条件(1)和(2)单独都不充分,但条件(1)和条件(2)联合起来充分.
D.条件(1)充分,条件(2)也充分.
E.条件(1)和条件(2)单独都不充分,条件(1)和条件(2)联合起来也不充分.