74．The parents are anxious about the ____________ (安全) of their missing child.
73．Don’ be ____________ (紧张) when you take an exam．
72．My mother was busy ____________ (准备) supper when I arrived home．
71．In the primary school, we learnt to recite many ____________ (诗).
70．The old woman lives alone and often feels ____________ (寂寞)．
69．Students’ smoking is ____________ (禁止) in most schools.
68．The room is not large enough for ____________ (九十) guests.
67．I will go to the party if I ____________ (收到) the invitation．
根据所给汉语提示用适当的单词完成句子。(每空只写一个单词)
66．Great changes have taken place in the 20th ____________ (世纪) in China.