can we trust online investment sites?are they worthy?

That depends on the site you're going to invest in. HYIP of course is not advisable unless you're a real risk taker and knows when to invest and cashout. But there are revenue-sharing programs and even money-cyclers that are worth investing into, as compared to investing on Bux sites for upgrade or referral rentals.

we cannot trust all the investment sites but there also good sites like exincome.......but its not clever investing in these kind of sites

There are some online investment site which we can truth. But all investment sites are not legit. You can ask others online whether a particular site is legit or scam. I also have plan to invest some money online.