This grammar exercise tests your ability to use different verb forms correctly. Fill in the blanks with an appropriate verb form.

1. A team of US scientists ………………. how bacteria communicate with each other.

a) discovered
b) has discovered
c) had discovered

2. Robots ……………… more and more like their human inventors.

a) becoming
b) are becoming
c) became

3. This website …………………. at creating a vibrant community of students.

a) is aimed
b) aimed
c) has aimed

4. Twendy –One is a robot ……………. to help disabled people and the elderly around the house.

a) is designed
b) designed
c) designing

5. Scientists …………….. stem cells from skin cells.

a) have developed
b) are developed
c) have been developed

6. New techniques in stem cell research ……………… reprogramming cells.

a) involve
b) involves
c) is involving

Answers

1. A team of US scientists have discovered how bacteria communicate with each other.

2. Robots are becoming more and more like their human inventors.

3. This website is aimed at creating a vibrant community of students.

4. Twendy –One is a robot designed to help disabled people and the elderly around the house.

5. Scientists have developed stem cells from skin cells.

6. New techniques in stem cell research involve reprogramming cells.