The scientist _____ Canada and he will giveus a talk when he _____ back.

－ 一Yes．I’d like beef,rice,potato soup and orange juice．

下列各组中有错别字的一项是

Nuclear science should be developed to guard peace ____ destroy the world[ ]

you find the missing couple in the mountainyesterday——No, but we _____ to get in touch with them eversince.