学校教室中六盏灯的连接方式是（ ）

用一水平力F将两铁块A和B紧压在竖直墙上而静止，如图所示，对此，下列说法中正确的是（   ）

设集合A={0，1}，B={-1，0，a+3},且A$\subseteq$B，则a=（  ）

    There's not just one reason why kids can't fall asleep, though, so there's also more than one____.

    If there's anything about your room that makes you feel ____ at night, like a picture that looks strange in the dark, or a noisy tap that leaks drop after drop, be sure to ask one of your parents if it can be moved or fixed.

    It may not____ make sense why something bothers you, but if it's keeping you from sleeping, it should be changed. Another idea could be getting ready for bed earlier than usual. Try to take more time to ____ by taking a warm bath, or listening to a bedtime story at least30 minutes before you want to go to sleep.