I’ll put it this way to sum it up. In most businesses, the good people far outnumber the bad people. But in this business, bad guys rule. Marcello is one of the good guys and his reviews prove it. I say one of the good guys because I know there are others out there, I just haven’t seen any yet. Go with DTA and you can thank me later. Now the nand version (top) of Figure 3.4(b): the input to the second gate is clearly , and we already know that, connected like this, the second nand gate performs negation, and two negations cancel, hence AB. I was a student of online trading accedamy. The class was interesting at first, but I fond it hard to follow because many of them are aganst trend tradings. Also if you like them, just take the class, don't spend money on the extended learning stuff, you won't get anything from there, just repeating the class stuff. The option trading class was a total failure, I throw them away and learned from many free website and doing much better than before. Another comments. Their site was always doing maintainence during morning busy hours when people need them most. Most likely it is down.