It is imperative that they arrive on time for the lecture.

Because of his low IQ the pre-school student was often goaded by his teachers to try harder.

We were told to intermingle with the guests.

Pets sometimes imitate their owners, but seldom the other way round.

The successful use of antitoxins and serums has virtually eradicated the threat of malaria, yellow fever, and other insect-borne diseases.

People living along the coast escaped inland before the hurricane hit.

The area is roped off because the water is contaminated.

According to most geologists, the universe is now about 15 billion years old.

The professor reprimanded the tardy student.

When the museum unveiled its plans, it expected a violent reaction.