，when Marx was already ，he began to learn Russian.

As the busiest woman in Norton, she made _____ her duty to look after all the other people’s affairs in that town.

It disappoints the specialists that Canada is faced with the similar problem as the Internet meant to bring people closer to set them apart.

Few people have ever ________ deep into this forest, for it is extremely dangerous.[ ]

It sounds like something is wrong with the car’s engine.________，we’d better take it to the garage immediately.