A calf is a young cow. A young female cow, especially one that has not yet had a calf, is called a heifer: H-E-I-F-E-R.

VOA: special.2009.07.21

And so this is the H-F bond in HF.

所以这是氟化氢中的氢氟共价键。

麻省理工公开课 - 固态化学导论课程节选

All right, so the type of bond energies that we can go and look up in tables are individual atom bonds, H-H, F-F, and the like.

好的，键能的类型,我们能够在表中查到,都是独立的原子键，H-H，F-F以及类似的。

麻省理工公开课 - 固态化学导论课程节选