Be careful about those who use the truth to deceive. When someone tells you something that is true, but leaves out important information that should be included, he can create a false impression.
For example, someone might say, "I just won a hundred dollars on the lottery (彩票). It was great. I took that dollar ticket back to the store and turned it in for one hundred dollars!"
This guy's a winner, right? Maybe, maybe not. We then discover that he bought two hundred tickets, and only one was a winner. He's really a big loser!
He didn't say anything that was false, but he left out important information on purpose. That's called a half-truth. Half-truths are not technically lies, but they are just as dishonest.