Help Dr. Von Quark finalize the safety protocols for his new time machine by choosing the correct verb form for each gap.

It is imperative that the temporal capacitor remain completely submerged in pickle juice.

I strongly recommend that my assistant, Igor, be wearing his lead underwear when the countdown begins.

Furthermore, I dictate that the dimensional portal not be opened until after lunch.

It is imperative that the temporal capacitor remain completely submerged in pickle juice.

Adjectives expressing urgency or necessity (like "imperative") trigger the subjunctive in the following that-clause. We use the base form of the verb ("remain") without an "-s".

I strongly recommend that my assistant, Igor, be wearing his lead underwear when the countdown begins.

Verbs of recommending trigger the subjunctive. Here, we need the continuous subjunctive form, which is "be" + present participle ("be wearing").

Furthermore, I dictate that the dimensional portal not be opened until after lunch.

This gap requires both the negative and passive subjunctive. We place "not" before the base form "be", followed by the past participle "opened".