But for other English speakers, the initial sounds in "do" and "tool" are similar to the hard д and т
T in tool is similar to Russian т, ть, ч in one and the same time. So, Ammonite, don't use those English sounds in Russian at all.
And thin is by no means tin (or sin), and bad is by no means bed. But for Russians who are new to learning English, those words can seem almost like homophones!
Not only to beginners. Especially bad and bed. That's why I warn Ammonite not to confuse those sounds.