Simple Present, Present Continuous Past, or Past Continuous.
Part 1:
Situation: Right now Tommy (is sitting) ... at the desk. He (is writing) ... in his
grammar workbook. His roommate, Bert, (is sitting) ... at his desk, but he
(is not studying) ... He (is staring) out the window. Tommy (wants)... to know what
Bert (is looking) ... at. Here is the dialogue:
T: Bert, what (are you looking) ... at?
B: I (am watching) ... the bicyclists. They are very skillful. I (do not know)
... how to ride a bike, so I (admire) ... anyone who can. Come
over to the window. Look at that guy in the blue shirt. He (is steering) ...
his bike with one hand while he (is drinking) ... a coke with his other. And
all the while, he (is weaving) ... in and out of the heavy street traffic
and the pedestrian traffic. He (seems) ... fearless.
T: Riding a bike (is not) ... as hard as it (looks) .. I'll teach you to ride a bicycle if you'd like.
B: Really? Great.
T: How come you don't know how to ride a bike?
B: I never (had) ... a bike when I (was) ... a kid. My family (was) too
poor. One time I (tried) ... to learn on the bike of one of my friends,
but the other kids (laughed) ... at me. I never (tried) ... again because I
(was) ... too embarrassed. But I'd love to learn now! When can we start?
Part 2
Yesterday Tommy (was sitting) ... at his desk and (writing) ...in his grammar
workbook. His roommate, Bert, (was sitting)... at his desk, but he (was not studying)
... He (was staring) ... out the window. He (was watching) ... bicyclists on the
street below. Tommy (walked) ... over to the window. Bert (pointed) ... out
one bicyclist in particular. This bicyclist (was steering) ... with one hand
while he (was drinking) ... a with the other. And all the while, he (was weaving) ...
in and out of the heavy traffic. Bert never (leart) ...
how to ride a bike cyclist (seemed)... fearless. when he (was)... a kid,
so Tommy (offered) ... to teach him how. Bert (accepted) ...gladly