If these trousers are too short, buy a longer_______.
A. one       B. pair        C. ones

In real life, robots are mainly used in factories. They do many different jobs. Usually these jobs are too   43 , difficult or boring for humans.
Robots also help disabled people and people who cannot look after   44 . For example, scientists are making a robot to help blind people. Now many of them have a dog to help them. The dog is called a guide dog. In the future, guide dogs might be robot dogs.
One robot dog is called Meldog. It has wheels. It usually “walks” in front of its owner. It is very clever. It knows the speed of its owner’s walk. Meldog talks to its owner by   45 . The owner wears a special belt. This belt   46  instructions to the owner from Meldog such as “Stop here”, “Turn left” and “Turn right”.
In the United States, another   47  of robot helps disabled workers. This robot, called Kilroy, helps disabled computer operators. The robot   48  the sound of its owner’s voice. It follows instructions such as “Turn the page” and “Make a cup of coffee”.
Robots are also used in American   49 . They can do simple jobs. For example, they shave (刮脸) patients and brush their teeth and take meals from the kitchen to patients’ rooms. It never gets lost   50  this robot has a map of the hospital in its computer memory.

If these trousers are too short, buy a longer_______.

A. one       B. pair        C. ones

根据句意，用所给单词或短语的适当形式填空。（每词或短语只限使用一次）。

1.These shoes are too big for my ________.

2.It is a _______ day. Let’s go outside and play.

3.In spring, I often ________ in the Red Star Park.

4.Michael _______ his old friend Lily this morning.

5.Susan will sing some pop songs at her ______ concert.