The voyages of travellers before the 17th century show that they were not ________ the sea even though they didn’t have modern navigational aids[ ]

It’s rather hot in the room. You’d better thewindows or the door.

This accident (事故) happened (发生) ________ a winter afternoon.

Miss Yang doesn’t look well. What’s wrong with her— Oh, she has some trouble______ her baby well.

How ______ you spell it______.