future perfect and continuous

[Luxindius]

I have a problem because I don´t know when in a sentence I have to put continuous or perfect.
for example
Why are you turning on the TV? I think I_______________ a cheese sandwich.(have).
Did you get the bread? oh no! Sorry, I forgot. I ____________________ it now (go)
Have you seen John recently? No, but I____________ him at 7p.m(meet).
Where is EVA?OH, she _________________ she always is! (be)

[Tespineli]

I am not sure of the first and the fourth but let me answer the second and the third.

2) Did you get the bread? oh no! Sorry, I forgot. I am going to get it now. or I am getting it now.
EXPLANATION: Inside the sentence you showed the timing "now" which is used in present continuous sentences.

3) Have you seen John recently? No, but I met him at 7 p.m.
EXPLANATION: There is a specific time stated so we use the simple past of meet which is met.

I hope this helps. :)