从2007年4月18日零时起，全国铁路进行第6次大提速后，将进一步增大铁路边上行人的危险性．这是由于行人和高速行驶的列车之间的空气流速____ ，压强____ ，由此产生的压力差将人推向火车，危及行人的生命安全．因此，铁路部门在设置黄色安全警戒线时应该离列车适当比原来____ （填“远”或“近”）一些．

可以证明生长素低浓度促进生长，而高浓度抑制生长的例子是 （    ）　

       Last week our class went to the zoo as part of our science project. We spent a few hours1there. We didn't do much studying. We just had a good 2 . We left for the zoo by bus at 9:00 and 3 at the zoo half an hour later. There are all kinds of 4 in the zoo. And the animals have many good 5 for us. We all wanted to watch the elephant show at 10:00. But before that we went to look at snakes because it was a part of our project. I don't like snakes because they are so 6. The elephant show lasted 45 minutes. It was really nice. I didn't know elephants can play soccer so 7! Then we had a 15-minute break for a drink, we went 8  the zoo trying to see as many animals as we could before 9. Lunch was fun because we had it 10 monkeys. We went back on the bus at 2:00. It took 30 minutes to get back to school.