Most scientists believe that perpetual motion devices can never be invented, but people come up with new ideas for them all the time. Do you think people should keep trying? Why?

Embryos of different species look very similar, which shows that the organisms share a ancestor.

Is this a single replacement reaction or there is no

There is one girl i like and i don't know how to tell her that, i have a feeling she knows but if she doesn't i don't want to make a fool out of myself how is one way to boost my confidence on asking her out