5. Complete the sentences with the correct form of the verb in brackets. 1 If it ..... (not rain), the plants die. 2 If you run, you ..... (catch) the train. 3 I'm sure he'll come if you ..... (invite) him. 4 If you ..... (drop) ice in water, it floats. 5 I ..... (call) you if I finish work early. 6 Unless you ..... (study) hard, you will fail the exam.

Here are the completed sentences with the correct verb forms, along with explanations: 1. **If it doesn't rain, the plants die.** *Explanation:* This is a zero conditional sentence (If + present simple, present simple), used to describe general truths or facts. Therefore, we need the present simple negative form of "rain," which is "doesn't rain." 2. **If you run, you will catch the train.** *Explanation:* This is a first conditional sentence (If + present simple, will + infinitive), used to describe a possible condition and its probable result in the future. So we use "will catch." 3. **I'm sure he'll come if you invite him.** *Explanation:* This is similar to a first conditional, expressing a probable outcome. The verb "invite" needs to be in the present simple tense. No changes are required. 4. **If you drop ice in water, it floats.** *Explanation:* This is a zero conditional sentence describing a general truth (If + present simple, present simple). The verb "drop" needs to be in the present simple. 5. **I will call you if I finish work early.** *Explanation:* This is a first conditional sentence (If + present simple, will + infinitive) describing a possible future action. The verb "call" needs the "will" auxiliary before it. 6. **Unless you study hard, you will fail the exam.** *Explanation:* This sentence uses "unless" which means "if...not." It combines with the present simple tense to create a conditional statement resulting in a future outcome. The verb "study" needs to be in the present simple.