Our neighbor offered to look after our baby yesterday when we were busy, _____is often the case.

I am very grateful to my high school teachers, without _____help I wouldn’t be so excellent.

  The hottest continent, Africa has a lot of resources, ______ are still undeveloped.

The number of various educational programs is increasing, _______ important roles have been realized by more and more people.

It was in the lab ______ was newly built ______ they carried out the experiment.

The well-known director, two of________ films won Oscar awards, is said to have retired.

He is such a clever student _________ everyone likes.

---Why does Jane always ask you for help?
---- There is no one else ________, is there?

Now there is just one point ________ I wish you to make quite clear.

Everyone will go through life's stages of ups and downs, ________ self­respect plays a key role in the maturity(成熟) of a person.