从安全、环保、节能、简便等方面考虑，实验室制取氧气的最佳方法是（     ）

有人比喻英国“像海绵一样从恒河边上吸取财富，又挤出来倒在泰晤士河中。”这句话提示了(   )

在下列各句的每个空格内填上一个适当的完整的单词，该词的首字母已给出。
①Remember always be p____   with these poor kids. They need our care and love.
②Don't l____ heart when you are in danger.
③The man p____  the sick child with some food last night, and now the boy is much better.
④Hope Project has sent many s____  designed(设计) computers to some schools in poor areas.
⑤The teenagers in the 21st c____  are much more different as we thought.

eleven—____—thirteen—____