It is difficult to write rules that tell exactly when we should apologize, and it is not difficult to learn how to do it.

There are many reasons why a particular species may become endangering.

After spending two days arguing about where to go for their holidays, is was decided that they shouldn’t go anywhere.

This apprentice has spent two weeks to work on that new machine.

Passengers are required to arrive to the gate fifteen minutes before departure time.

Not one in one hundred children exposed to the disease are likely to develop symptoms of it.

By the time Robert will finish writing the first draft of his paper, most of the other students will have completed their final draft.

I am now in my attempt winning a place at the same university to my brother.

Mr. Smith, along with her cousins from Canada, are planning to attend the firework display in Da Nang, Vietnam.

The chemistry instructor explained the experiment in such of a way that it was easily understood.

Dinosaurs became extinct millions of years ago because of the earth's climate changed drastically.

Species like snakes, lizards, coyotes, squirrels, and jack rabbits seems to exist quite happily in the desert.

Once you have finished an article and identified its main ideas, it may not be necessary to reread it again.

The amount of women earning Master's Degrees has risen sharply in recent years.

Slowly and with care, the museum director removed the Ming vase from the shelf and placed it on the display pedestal.

Because her sickness she didn’t take part in the English competition held in Sunday.

Looking from afar, the village resembles a small green spot dotted with tiny fireballs.

Because blood from different individuals may different in the type of antigen on the surface of the red cells and the type of antibody in the plasma, a dangerous reaction can occur between the donor and recipient in a blood transfusion.

Upon reaching the destination, a number of personnel is expected to change their reservations and proceed to Hawaii.

There are many different ways of comparing the culture of one nation with those of another.

Some of my friends are good at English while other are good at Mathematics.