John often takes a walk _______ his grandpa after dinner.
A.to B.for C.along D.with
Would you mind care of my pet fish while I'm away on holiday?
A. take B. taken C. to take D. taking
（2017·四川德阳·33）My mother has taught in this school________ she was twenty years old.
A.for B.until C.because D.since
-What is your mother doing, Linda?
-She ___________dinner in the kitchen now.
A.is cooking B.was cooking C.cook D.cooking
Dingtalk is a tool _______ is mainly used for teachers and students to have online classes during the fight against the novel coronavirus.
A.which B.who C.where D./
He isn't at school. I think he ___ be ill.
A.can B.shall C.must D.has to
