participle 同 past tense

magazines intended chiefly for teenagers= magazines that are intended chiefly for teenagers
(1) 主要為青少年而設的雜誌 (intend for = 為...而設)

(2) "intended" is a past participle. "intended chiefly for teenagers" is a participle phrase modifying "magazines".

(3) 例句: (clause ====> phrase) transformation

traps that are intended for the elderly (passive voice)
===> traps intended for the elderly (past particple)

policy that benefits the elderly (active voice)
===> policy benefiting the elderly (present participle) 對長者有益的政策

"intended marriage" = 預期的婚姻 (結婚典禮)
("intended" is an adjective)

Past participle can be used as a part of the main verb in continuous tense and in passive voice. It can also be used as an adjective.
The thief has stolen his bike. (Present perfect tense)
His bike was stolen. (Past simple tense;passive voice)
How can you mend a broken heart? ~ (broken - adj.)

Participle refers to verb form. There are 2participles, namely Present Participle and Past Participle. PresentParticiple:It is formed by adding “ing” to the base verb, eg. writing, barking…….,Itcan be used as the main verb of a sentence, eg. he is writing aletter. (“is” is helping verb).Itcan also be used as an adjective, eg. the barking dog is mine. PastParticiple:Verb form of Past Participle varies, eg. written, sung, cooked, run…..Itcan be use as the main verb of a sentence, eg I have written aletter. (“have” is a helping verb).Itcan also be used as an adjective, eg. I put the cooked food inthe refrigerator. Tense of a sentence indicatesthe complex temporal relationship ofactions, events, and conditions.eg. I wrote a letteryesterday, indicates the action toke place in the past and the time is known.eg. I was writing a letterwhen he came, indicates one action was going on while another action tokeplace.... Google internet or refer to grammarbooks for more examples.