Proper exercise is good for your health._____, too much is bad for it.

Since Tom_____ downloaded a virus into his computer, he can not open the file now.

Mike was usually so careful, ______this time he made a small mistake.

--How about this dress, sir? --It’s a little expenseive, and ____, its color doesn’t suit me.

______ acupuncture developed, the simple “bian stones” were replaced first by stone  and pottery needles, and ________ by metal needles.