These single-celled survivors called extremophiles, don’t merely endure environments too severe for other life forms; they thrive in them. Heat-loving extremophiles, or thermophiles, flourish in temperatures over 150 degrees Celsius.

Stay in the present tense.

As the potter takes bricks away to create an opening into the oven, an expanding view of gleaming shapes rewards the artist for months of hard work.

NOT Acceptable: Rosie, it turns out, is a desert tortoise that my grandmother had started up raising over twenty years ago.

My aunt said that she had checked with my parents, who each agreed that if I wanted to take responsibility for Rosie, I could take her home with me.

The conversation with the parents occurred in the past.

In 1753, at the age of twenty-two, Banneker displayed his interest in learning and his mechanical skills when he constructed a clock out of handcarved wooden parts. The clock kept precise time for—can you believe it?—over forty years.

Since events begin in 1753, the 40 years is past (kept) not ongoing (has kept).

Equipment for both types of kayaks is similar and fairly simple.