export first in a sentence

1. Nuclear export first begins with the binding of Ran-GTP ( a G-protein ) to exportin.
2. Iraq exports first oil since U . S .-led invasion, marking return to world oil market.
3. Nov . 30 Trade Day celebrates the date in 1964 when South Korean exports first exceeded US $ 100 million.
4. It's difficult to find export first in a sentence.