The biggest cell in the embryo sac is the central cell.

胚囊中最大的细胞是中央细胞。

The yolk sac is necessary for fetal development.

卵黄囊是胎儿发育必需的。

The bombing operation destroyed the enemy's SAC.

这次的轰炸行动摧毁了敌人的战略空军司令部。

The sac is a part of a plant or animal that is like a bag and often contains liquid.

囊是植物或动物的一部分 像一个袋子 通常含液体

More than 750,000 have graduated from SAC, with many seeking employment in engineering, aviation, education and a wide variety of other professions.

超过75万人从SAC毕业，其中许多人在工程、航空、教育和其他各种领域中寻找工作机会。

Chris has talked about pandas being an evolutionary cul-de-sac, and it's certainly unusual for a carnivore to take up herbivory.

克里斯曾经说熊猫是进化的尽头，而对于食肉动物来说，摄取食草动物是很不寻常的。

More than 750,000 have graduated from SAC(Space and Aviation Center), with many seeking employment in engineering, aviation, education, medicine and a wide variety of other professions.

超过75万人从航天中心毕业，其中许多人在工程、航空、教育、医学和其他各种专业上寻求就业机会。

Extraembryonic mesoderm migrates through primitive streak to the presumptive yolk sac between days 6.5 and 7.0 of gestation.

胚外中胚层在妊娠的第6.5至7.0天之间通过原始条带迁移到推测的卵黄囊。

Some of the models contained an air sac.

其中一些模型含有气囊。