You must ________ what the teacher explains in the class, or you will not be able to grasp the main points of the knowledge.[ ]

Tom wants to be a singer and he_____ singing lessonsto do it.

Einstein liked Bose’s paper so much that he _____ his own work and translated it into German. [ ]

The boy saved all his classmates in the earthquake. ________brave he was!

Excuse me. May I speak to Jill， please —________________.