Copy the expression ___________, please, without any changes.

When ______ comes to research into heart disease and its effects on the body, we do not have adequate substitutes for the use of animals.

As we grow up, it always _______ that after we give something up, we gain something new in its place.

____some doubt among scientists about the cause of cancer.

—Were all the supplies for the people carried to the flood-stricken areas?—No,      only some of them      nearly all the roads there cut off.