What is the authors opinion? A- huge stockpiles of destructive weapons have so far saved mankind from catastrophe.
B- Superpowers have at last realized the need for abandoning in the production of lethal weapons.
C- Mankind is heading towards complete destruction.
D- There is a silver lining over the production of deadly weapons.

American history (is, are) studying the american colonies.

Lisa works 7 hours a day, 7 days a week. how many hours does lisa work in 6 weeks

Walking is not the most exciting form of exercise a person can take on for fitness. yet it is low impact and requires no fancy equipment. that makes walking a simple activity for those new to exercise. walking is less likely than other exercises to cause injury to leg tendons and muscles. all it requires is a good pair of sneakers-no cables, stylish outfits, or weights required. of course, a person could increase the benefit of a workout by adding weights or speed walking. identify the main idea of this paragraph. walking is a difficult and safe exercise for beginners. walking is an easy and safe exercise for beginners. walking is a boring and dangerous form of exercise. walking is an exciting and very effective form of exercise.