Tenses Worksheet For Classes 9 and 10

Fill in the blanks with an appropriate tense form of the verb. This grammar exercise is useful for high school students.

Tenses Worksheet for Classes 9 and 10

The system ……….1……….. only a point-and-shoot or video camera that ………….2……….. high-resolution pictures of people’s faces. Computers can then analyze these images ………….3………… where the people are looking.

To do this, a computer program …………4………….. the line where the iris (the colored part of the eye) ……………..5…………… the white of the eye. If you look directly at a camera, your cornea ………………6……………… perfectly round. But as you glance to the side, the angle of the curve ……….7…………. A formula …………8………….. the direction of the eye’s gaze based on the shape of this curve. Next, the program ………….9…………… the direction from which light is coming as it hits the eye and bounces back to the camera. The computer uses all this information to create an environment map of everything …………..10…………… the eye.

1. a) is requiring; b) required; c) requires; d) has required
2. a) is taking; b) takes; c) has taken; d) took
3. a) to determine; b) determining; c) to determining; d) determine
4. a) identifying; b) identifies; c) is identifying; d) has identified
5. a) meets; b) is meeting; c) has met; d) met
6. a) appears; b) appeared; c) will appear; d) would appear
7. a) is changing; b) has changed; c) changes; d) would change
8. a) calculate; b) calculates; c) has calculated; d) calculated
9. a) has determined; b) determines; c) is determining; d) determine
10. a) surround; b) surrounding; c) surrounded; d) surrounds

Solution

The system requires only a point-and-shoot or video camera that takes high-resolution pictures of people’s faces. Computers can then analyze these images to determine where the people are looking.

To do this, a computer program identifies the line where the iris (the colored part of the eye) meets the white of the eye. If you look directly at a camera, your cornea appears perfectly round. But as you glance to the side, the angle of the curve changes. A formula calculates the direction of the eye’s gaze based on the shape of this curve. Next, the program determines the direction from which light is coming as it hits the eye and bounces back to the camera. The computer uses all this information to create an environment map of everything surrounding the eye.

Notes

Use the simple present tense to talk about facts. You can find an overview of the simple present tense here