This is provided by the surrounding skull and three tough membranes called meninges.

它被包围着的颅骨和三层坚韧的细胞膜被称作脑（脊）膜保护着。

youdao

Last night, while travelling home on the underground, I saw three tough guys enter my almost empty carriage.

昨晚乘地铁回家时，我看见三个粗暴的家伙走进我坐的车厢，几乎是空的。

youdao

Mr. Cilic "played three five-set matches and made it so tough for me and fought until the end."

西里奇说“打了三场都是五局的比赛让我有点吃不消，我会战斗到最后。”

youdao

Those were really tough tours. They were kept out very often for up to three months, under some pretty grueling conditions.

VOA: special.2010.06.21

He lists three essentials for life on this tough new planet: food,energy and the Internet.

VOA: standard.2010.04.21

Thirteenth seed Daniela Hantuchova went through after three tough sets against Luxembourg's Anne Kremer.

BBC: SPORT | Tennis | Clijsters eases into third round

Williams will now meet Kim Clijsters in the final, after the Belgian saw off compatriot Justine Henin in three tough sets.

CNN: Venus beats Bartoli to seal Miami final berth

Gupta opened the door - and three tough young hoodlums slammed into him and his younger brother Kanhaiya Lal, who had been wakened by the commotion.

CNN: TRAPPED IN THE BIG SQUEEZE