2、.答案: frequently3.Youcantellfromthe________(express)onhisfacethathedidn’tdoverywellintheexam.答案: expression4.Teachers________(rich)theirknowledgewhileteachingtheirstudents.答案: enrich5.Theyarefacedwiththesamekindsofchallengesandproblemsinlife________youare.答案: as