想表达“我正在XXX公司实习中”
I'm doing an internship at XXX.
I'm an intern at XXX.
ref:
http://www.usingenglish.com/forum/threads/157504-taking-vs-doing-an-internship
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“我曾经在XXX公司实习”
I had an internship with ...
I did my internship with...
I did my internship in ...
I was an intern at ...
ref:
http://forum.wordreference.com/showthread.php?t=508117&langid=22