how many categories are there in engineering? (1 comment)

What deternines the sex of an infant while in the womb? (1 comment)

How do cellphones work with the use of radio waves and how are they interconnected (1 comment)

Apart from the nine planets, are there other planets? And if so do they support life? (1 comment)

clotting of blood happens out side the body ,why does blood not clot inside the body (1 comment)