【简答题】We have days and nights because of _____of the earth.
【简答题】We have problem with evaluating risk partly because ______.
【单选题】We may have dreams because we have needs that are _____ in our daily lives.
【简答题】Because we human beings have sophisticated and personalized brains, we have the notion of self.
【单选题】We have no time to have a rest on Sundays, because ourteachers _______ us do a lot of homework.
【单选题】We can't go home _____ the heavy rain and we have to wait _____ it stops. [ ]
【判断题】气体燃料中的可燃成分在一定条件下与氧发生激烈的还原反应,并产生大量的热和光的物理化学反应过程称为燃烧。
【简答题】氯气(Cl 2 )通常情况下为有强烈刺激性气味的黄绿色的气体,具有强氧化性,一定条件下可与除Pt、Au外大部分金属反应.氢气在氯气中能安静地燃烧,发出苍白色火焰,而红热的铜丝在氯气里剧烈燃烧,冒出大量的棕黄色的烟.请根据资料回答下列问题: (1)根据上述资料提供的信息,你对燃烧有什么新的认识?______. (2)氯气的活动性比氧气的活动性______(填“强”或“弱”). (3)与金属相似,活泼...
【单选题】血吸虫感染集中发生在每年的哪几个月。( )