| singular | plural |
| Infinitive | | |
| observe | |
| present simple | | |
| 1 | I observe | we observe |
| 2 | you observe | you observe |
| 3 | he/she/it observes | they observe |
| past simple | | |
| 1 | I observed | we observed |
| 2 | you observed | you observed |
| 3 | he/she/it observed | they observed |
| future simple | | |
| 1 | I will/shall observe | we will/shall observe |
| 2 | you will/shall observe | you will/shall observe |
| 3 | he/she/it will/shall observe | they will/shall observe |
| conditional simple | | |
| 1 | I would observe | we would observe |
| 2 | you would observe | you would observe |
| 3 | he/she/it would observe | they would observe |
| present continuous | | |
| 1 | I am observing | we are observing |
| 2 | you are observing | you are observing |
| 3 | he/she/it is observing | they are observing |
| past continuous | | |
| 1 | I was observing | we were observing |
| 2 | you were observing | you were observing |
| 3 | he/she/it was observing | they were observing |
| future continuous | | |
| 1 | I will be observing | we will be observing |
| 2 | you will be observing | you will be observing |
| 3 | he/she/it will be observing | they will be observing |
| conditional continuous | | |
| 1 | I would be observing | we would be observing |
| 2 | you would be observing | you would be observing |
| 3 | he/she/it would be observing | they would be observing |
| present perfect | | |
| 1 | I have observed | we have observed |
| 2 | you have observed | you have observed |
| 3 | he/she/it has observed | they have observed |
| past perfect | | |
| 1 | I had observed | we had observed |
| 2 | you had observed | you had observed |
| 3 | he/she/it had observed | they had observed |
| future perfect | | |
| 1 | I will have observed | we will have observed |
| 2 | you will have observed | you will have observed |
| 3 | he/she/it will have observed | they will have observed |
| conditional perfect | | |
| 1 | I would have observed | we would have observed |
| 2 | you would have observed | you would have observed |
| 3 | he/she/it would have observed | they would have observed |
