Step-by-step explanation:
A: When’s Barbara going to call? We have to leave soon.
B: She *could call* any minute. I’m sure she’ll call us before we *go*.
The correct verb forms to use in this context are 'could call' and 'go'. This is because the sentence is talking about a possibility of something happening (Barbara calling) and a future action that depends on it (leaving soon). Using 'could call' expresses that it is likely for Barbara to call soon, while 'go' is the base form because it follows the auxiliary verb 'will', indicating a future action.