问题
选择题
They _ the train until it disappeared in the distance.
A．saw
B．watched
C．noticed
D．realized
答案
答案：B
题目分析：句意：他们看着火车直到它消失在远方。Saw看，看见；watched 观看； noticed注意；realized意识到。所以选B。
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They _ the train until it disappeared in the distance.
A．saw
B．watched
C．noticed
D．realized
答案：B
题目分析：句意：他们看着火车直到它消失在远方。Saw看，看见；watched 观看； noticed注意；realized意识到。所以选B。
下面是某兴趣小组探究同质地同数量的烟草在不同体积水中浸出液对水蚤心率影响时记录的数据，请回答问题
清水 | 烟草浸出液 | |||||
| 70mL | 60mL | 50mL | 40mL | 30mL | ||
| 20秒内 心跳次数 | 60 | 63 | 65 | 67 | 69 | 71 |
（2）简述吸烟对青少年健康的影响．答案及评分标准：______．