is in hospital— Oh, really I _____________ know I_______________ go and visit her

Although he is very old, _________ he works very hard.

How many ________are there in your school

great progress it has made since Hong Kong returned to China in 1997.

When he was alive, the old scientist used to say that knowledge ＿＿＿＿from practice and he gained his experience by doing a lot of practical work