do I observe? do you observe? does he observe? do we observe? do you observe? do they observe?
Present continuous
am I observing? are you observing? is he observing? are we observing? are you observing? are they observing?
Preterite
did I observe? did you observe? did he observe? did we observe? did you observe? did they observe?
Preterite continuous
was I observing? were you observing? was he observing? were we observing? were you observing? were they observing?
Present perfect
have I observed? have you observed? has he observed? have we observed? have you observed? have they observed?
Present perfect continuous
have I been observing? have you been observing? has he been observing? have we been observing? have you been observing? have they been observing?
Pluperfect
had I observed? had you observed? had he observed? had we observed? had you observed? had they observed?
Pluperfect continuous
had I been observing? had you been observing? had he been observing? had we been observing? had you been observing? had they been observing?
Future
will I observe? will you observe? will he observe? will we observe? will you observe? will they observe?
Future continuous
will I be observing? will you be observing? will he be observing? will we be observing? will you be observing? will they be observing?
Future perfect
will I have observed? will you have observed? will he have observed? will we have observed? will you have observed? will they have observed?
Future perfect continuous
will I have been observing? will you have been observing? will he have been observing? will we have been observing? will you have been observing? will they have been observing?
Conditional
Present
would I observe? would you observe? would he observe? would we observe? would you observe? would they observe?
Present continuous
would I be observing? would you be observing? would he be observing? would we be observing? would you be observing? would they be observing?
Past
would I have observed? would you have observed? would he have observed? would we have observed? would you have observed? would they have observed?
Past continuous
would I have been observing? would you have been observing? would he have been observing? would we have been observing? would you have been observing? would they have been observing?