Many. If there is no right angle it's not a rectangle...
It is NOT as case of 'Some'. It is ALL rectangles are parallelograms.
All rectangles are parallelograms, so yes there are some.
No. Only some parallelograms are rectangles. But all rectangles are parallelograms.
Some parallelograms are rectangles; all rectangles are parallelograms.
false
True
All of them are.
Some of them (rectangles) do.
yes, it is true
Yes.
Yes
yes