Not only us foreign scientists struggle with the English language when we give presentations or write papers or grant proposals. The native speakers also sometimes find themselves in difficult waters with their own language. Here’s an excellent article on the use of ‘which’ and ‘that’. It starts like that:

“I have a niggle,” says a reader. “My copy of the Guardian style guide clearly explains the difference between that and which, but this advice often fails to make it to the pages of the Guardian.” She quotes an example: “An overhaul of consumer protection rights, led by the consumers’ champion, Ed Mayo, is to be announced by Labour on Monday as the party moves to confront ‘bad companies’ which cheat customers.”

Go and read the whole thing and don’t start writing that manuscript before you’ve memorized it! :-)