1. market / tourism
The missing letter is t, forming market and tourism.

2. ground / diamond
The missing letter is d, forming ground and diamond.

3. urban / netizen
The missing letter is n, forming urban and netizen.

4. advice / expert
The missing letter is e, forming advice and expert.

5. suburb / button
The missing letter is b, forming suburb and button.

6. match / hurry
The missing letter is h, forming match and hurry.

7. drama / answer
The missing letter is a, forming drama and answer.

8. local / leader
The missing letter is l, forming local and leader.

9. factor / risky
The missing letter is r, forming factor and risky.

10. menu / uniform
The missing letter is u, forming menu and uniform.

11. perform / method
The missing letter is m, forming perform and method.

12. stamp / plastic
The missing letter is p, forming stamp and plastic.

13. nephew / watch
The missing letter is w, forming nephew and watch.

14. galaxy / youth
The missing letter is y, forming galaxy and youth.

15. status / subject
The missing letter is s, forming status and subject.

16. belief / foreign
The missing letter is f, forming belief and foreign.

17. swing / guide
The missing letter is g, forming swing and guide.

18. concert / target
The missing letter is t, forming concert and target.

19. network / knife
The missing letter is k, forming network and knife.

20. quiz / zero
The missing letter is z, forming quiz and zero.