Usually we have a set form which is printed.

通常是用事先印好的固定格式。

The fixed stars form sets or groups, to which names have been given.

这些恒星可以构成星群或星团, 而它们也都有自己的名称。

So an egg cell must be fertilized by a sperm cell to form two full sets of chromosomes.

因此，卵细胞必须由精子受精才能形成两套完整的染色体。

Propagation of the host organism containing the recombinant DNA forms a set of genetically identical organisms, or a clone. This process is hence known as DNA cloning.

宿主和载体。

One possibility is to form a second set of wings with the leg feathers straight back and the foot feathers spread horizontally, something like an old-fashioned biplane.

一种可能性是形成第二组翅膀，腿部羽毛笔直向后，脚部羽毛水平展开，有点像老式双翼飞机。