What is double fertilization (双受精)？And what is the biological significance （生物学意义） of double fertilization?

in vitro fertilization是指体外受精。（ ）

中国大学MOOC: what is in vitro fertilization?

what is in vitro fertilization? A: 体外受精 B: 胚胎培养 C: 受孕 D: 试管婴儿

‍人工授精的英文是（ ）。‌ A: mating B: breeding C: artificial insemination D: fertilization

What are the three ways plants bear fruits? A: Double fertilization B: Parthenocarpy C: Apomixis D: Pollination

Why do plants spread their fruits or seeds? A: For pollination B: For rooting C: For fertilization D: For offsprings growing better

Which of the following is wrong about the development of fertilized eggs? A: Zona pellucida reaction ensures single egg fertilization B: Egg swims in the fallopian tube and divides twice a day C: Egg moves in the fallopian tube and divides with its volume increasing D: Fertilized egg runs in the fallopian tube for 72 hours E: On the 4th day after fertilization, morula enters the uterine cavity

Insect reproduction may be characterized by all of the following EXCEPT: ( ). A: direct sperm transfer B: copulatory organs C: indirect fertilization D: an ovipositor of the female E: sperm storage in the sperm receptacle

体外受精即是将精子和卵子人为控制在体外完成受精过程发育成胚胎，再将胚胎移植给受体母亲，出生婴儿的技术。(In vitro fertilization (IVF) is a technology whereby sperm and ovum are artificially fertilized in vitro to develop into embryos, which are then transferred to the recipient mother to give birth to a baby.)