Tryptophan has to fight with other amino acids to cross the blood-brain barrier and get into the brain.

色氨酸必须打败其他的氨基酸，才能通过血管-大脑的障碍物，到达大脑。

youdao

But your servants, every man armed for battle, will cross over to fight before the Lord, just as our Lord says.

但你的仆人，凡带兵器的，都要照我主所说的话，在耶和华面前过去打仗。

youdao

He is a true hero who is ready to overcome difficulties bear hardships and fight courageous ly and resolutely to cross the Yangtze river.

真正的英雄，就是要克服困难，准备吃苦，准备勇敢坚决地打过长江。

youdao

The worst cases fight furiously against the Red Cross volunteers trying to help them, convinced the volunteers are the militias coming to kill them.

VOA: standard.2009.04.08

The minister also said the closures will have no impact on the fight against cross-border crime in all its forms.

BBC: Concern over Garda station closures in Irish border areas

Legend has it the Irish giant Finn McCool built the causeway to cross the sea and fight a Scottish rival.

BBC: Step forward for Causeway centre

Our home secretary is a member of that select club of politicians (founder members Denis Healey and Ken Clarke) who would cross the road to pick a fight.

BBC: Thursday 24 April