Brain, like muscles, also needs some kind of exercise and nutrition. The more you use your brain in the right direction, the more you ________ enhance your ability.
-Why does the water smell terrible? -Because large quantities of water __________.
I don't think it __________ to stay up late in the night and sleep until midday the next day.
The form cannot be signed by anyone __________ yourself.
In ancient times, people rarely travelled long distances and most farmers only travelled __________ the local market.
To improve the quality of our products, we asked for suggestions __________ had used the products.