Найдите в предложениях неличные формы глагола и назовите их:
a) Indefinite Infinitive Active;
b) Indefinite Infinitive Ibssive;
c) Continuous Infinitive Active;
d) Perfect Infinitive Active;
e) Perfect Infinitive Passive.

1. Input devices are used to enter data into primary storage.
2. These data appeared to have been investigated long ago.
3. We are glad to have obtained such valuable results.
4. You should have known wonderful features of computers long ago.
5. The problem to be solved is of great importance to the development of this branch of industry.
6. The first amplifying semiconductor devices (transistors) are known to have been
developed in the USA in 1948.
7. He ordered these devices to be repaired as soon as possible.

1. to enter (a) 2. to have been investigated (e) 3. to have obtained (d) 4. have known (d) 5. to be solved (b) 6. to have been developed (e) 7. to be repaired (b)