Which book is ______ to understand, this one or that one

often heard the ABC Song ________,but I have never heard Alice ________ it.

Have you finished your experiment report, Jane— Oh, my God. I’ve ________ forgotten all about that.

This isthe second time I_______ the Himalayas as a college student

___it is true that a student’smost important goal is to do well in his or her studies, it doesn’t need to bethe only goal.