题干

两位杂技演员,甲从高处自由落下的同时乙从蹦床上竖直跳起,结果两人同时落到蹦床上,若以演员自己为参考系,此过程中他们各自看到对方的运动情况是(   )

A:甲看到乙先向上,再向下运动

B:甲看到乙一直向上运动

C:乙看到甲先向下、再向上运动

D:甲看到乙一直向下运动

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答案(点此获取答案解析)

B

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阅读理解

    “Children start putting their fingers in their noses as infants,” says Sarah Springer, MD' of Kids Plus Pediatrics in Pittsburgh. “As soon as they have motor control of their fingers, they'll find holes where their fingers can fit. It's not a worry—just a normal part of how they explore and learn.”

    In order to help your child to stop engaging in the behavior it's important to understand why they may start the habit in the first place, according to the University of Michigan Health System. Nose-picking can be a result of boredom, sleepiness, falling asleep, relaxation or coping. In most instances, nose-picking is likely just a phase(阶段)and the child will eventually quit it.

    There isn't much parents can do to stop the behavior of nose-picking, as it's a normal part of being a kid, Dr. Springer says. Parents are advised to ignore the behavior and not show frustration's this won't help encourage your child to stop picking their nose. Instead, Dr. Springer says to help your child learn to blow their nose once they are four or five years old and talk to your child about keeping their hands clean to avoid spreading germs.

    Take note of the season or climate, too, as dry air or cold can increase the occurrence of nose-picking. Parents should use a humidifier(增湿器)in these conditions to help nasal secretions(鼻分泌物)stay moist. Putting petroleum jelly(凡士林)a few times a day inside the nose can help with irritation and minimize picking.

    Once your child enters school, it's inevitable for them to see and pick up bad habits, Dr. Springer said. Nose-picking is a common habit, even among adults and as children age most will realize it's not an acceptable behavior.

    “Nose picking is a normal part of childhood,” Dr. Springer says. “Most kids will become conscious of the social stigma(羞耻)associated with it, and will eventually stop picking, at least in public.”