First Conditional
http://www.perfect-english-grammar.com/first-conditional-exercise-1.html

Estructura:

If + present simple + futur simple (Will + infinitive)

Coses que, molt probablement, poden pasar en el futur

Exemples:
If it rains, I won't go to the park.
If I study today, I'll go to the party tonight.
If I have enough money, I'll buy some new shoes.
She'll be late if the train is delayed.
She'll miss the bus if she doesn't leave soon.
If I see her, I'll tell her.

1) If I (go) out tonight, I (go) to the cinema.

2) If you (get) back late, I (be) angry.

3) If we (not/see) each other tomorrow, we (see) each other next week.

4) If he (come) , I (be) surprised.

5) If we (wait) here, we (be) late.

6) If we (go) on holiday this summer, we (go) to Spain.

7) If the weather (not/improve) , we (not/have) a picnic.

8) They (go) to the party if they (be) invited.

9) If I (not/go) to bed early, I (be) tired tomorrow.

10) If we (eat) all this cake, we (feel) sick .

11) She (stay) in London if she (get) a job.

12) If you (not/want) to go out, I (cook) dinner at home.

13) I (come) early, if you (want).

14) He (not/get) a better job if he(not/pass) that exam.

15) I (buy) a new dress if I  (have) enough money.

16) She (cook) dinner if you (go) to the supermarket.

17) They (go) on holiday if they (have) time.

18) We (be) late if we (not/hurry).

19) She (take) a taxi if it (rain).

20) I (not/go) if you (not/come) with me.

Answers:
01 If I go out tonight, I will go to the cinema.
02 If you get back late, I will be angry.
03 If we don't see each other tomorrow, we will see each other next week.
04 If he comes, I will be surprised.
05 If we wait here, we will be late.
06 If we go on holiday this summer, we will go to Spain.
07 If the weather doesn't improve, we won't have a picnic.
08 They will go to the party if they are invited.
09 If I don't go to bead early, I will be tired tomorrow.
10 If we eat all this cake, we will feel sick.
11 She will stay in London if she gets a job.
12 If you don't want to go out, I will cook dinner at home.
13 I will come early, if you want.
14 He won't get a better job if he doesn't pass that exam.
15 I will buy a new dress if I have enough money.
16 She will cook dinner if you go to the supermarket.
17 They will go on holiday if they have time.
18 We will be late if we don't hurry.
19 She will take a taxi if it rains.
20 I won't go if you don't come with me.