dative covalent bond

1)
One pair of electrons is shared in a dative covalent bond.

2)
For a dative bond X→Y. The two bonded atoms are X atom and Y atom.

For example, consider a compound, H3N→BF3. The dative bond is N→B, and the two bonded atoms are N atom and B atom.

In the dative bond N→B, a pair of electron is shared which is supplied by the N atom.

3)
可以看成是 share 一對 electrons。而該對 electrons 來自其中一個 bonded atom 的 lone pair of electrons.

This is because 「share a lone pair of electrons」共用孤電子對是 contradictory。Lone pair means unshared pair, and it thus will become 「share an unshared pair of electrons」。