New words：

fasten [ˈfæs(ə)n] v.扣紧；盯住；盖好；使牢固

Sample Sentences：

The dog fastened its teeth in his leg.
She fastened the belt loosely around her waist.
She got quickly into her car and fastened the seat-belt.

New words：

steward [ˈstuərd] n.（飞机、轮船、火车等的）服务员；男服务员；乘务员
stewardess [ˈstuərdəs] n.（飞机、轮船、火车等的）女乘务员；女服务员

Sample Sentences：

The steward helped the old man find his seat.
The ship’s steward checked the passengers’ tickets.

The stewardess served meals during the flight.
The stewardess showed us how to fasten the seatbelt.

fasten [ˈfæs(ə)n] v.扣紧；盯住；盖好；使牢固

New words：

distinguish [dɪˈstɪŋɡwɪʃ] v.区分；辨别；分清；

Sample Sentences：

It was hard to distinguish one twin from the other.
I could not distinguish her words, but she sounded angry.
The male bird is distinguished from the female by its red beak.

New words：

agenda [əˈdʒendə] n.议事日程；议程；议程表

Sample Sentences：

Let’s follow the agenda to save time.
We need to finish the agenda before 5 o’clock.
For the government, education is now at the top of the agenda.

New words：

virus [ˈvaɪrəs] n. 病毒

Sample Sentences：

So far they have not found a way to fight the virus.
This software is designed to scan all new files for viruses.
Like the flu virus, a computer virus can spread all over the world.