Study the list:

Verb (verb)	Referential pronunciation (referénshal pronunciéishon)	Translation  (transléishon)	Past participle (past párticipol)	Referential pronunciation  (referénshal pronunciéishon)
36. Say	(séi)	Decir	Said	(Sed)
37. See	(si)	Ver	Seen	(Sin)
38. Sell	(sel)	Vender	Sold	(soúld)
39. Shake	(shéik)	Sacudir	Shaken	(shéiken)
40. Sing	(sing)	Cantar	Sung	(Sang)
41. Sleep	(slíp)	Dormir	Slept	(Slept)
42. Speak	(spík)	Hablar	Spoken	(spóuken)
43. Steal	(stíl)	Robar	Stolen	(stóulen)
44. Swear	(suér)	Jurar	Sworn	(suórn)
45. Swim	(suím)	Nadar	Swum	(suám)
46. Take	(téik)	Tomar	Taken	(teíken)
47. Teach	(tich)	Enseñar	Taught	(tot)
48. Think	(zink)	Pensar	Thought	(zot)
49. Win	(uín)	Ganar	Won	(uón)
50. Write	(ráit)	Escribir	Written	(ríten)

More examples:

a. A hunter had killed an elephant before the Chinese tourists saw it.
b. Blue whales had disappeared of the coast before they were protected by law.
c. She hadn’t seen a water turtle since they were declared in extinction.
d. Humans hadn’t adapted to share the planet with the rest of species, so they didn’t respect their habitat.
e. Had you visited the polar bear at the zoo before it had a baby bear? Yes, I had.
f. Had she taken pictures of the dead animal by the time I arrived? No, she hadn’t.

Exercise 1
(éksersais uán)

Make the positive or negative past perfect form. Read carefully and decide.

1. When I arrived at the cinema, the film . (start)

2. After they  (eat) the shellfish, they began to feel sick.

3. We were late for the plane because we  (remember) to bring our passports.

4. When we  (finish) dinner, we went out.

5. The lights went off because we  (pay) the electricity bill.

6. The children  (do) their homework, so they were in trouble.

7. Joseph  (bring) his tickets so we didn’t need to buy them.