22.____________ abroad　 for two years ,he will come back within two weeks

A Having studied 　B Studied 　C To study　 　D Studying

第一节：语法和词汇知识(共15小题；每小题1分，满分15分)

从A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该选项的标号涂黑。

21.A boy rushed in_____________he opened the door

A the moment　 　B for the moment　 　C for a　 moment　 　D at the moment