When V-ing....,it is adj to......?

[Aieda_Chiang]

(a)In Japan, when taking leave of a friend, it is customary to give a bow.
(b)In Japan, when people taking leave of a friend, it is customary to give a bow.
(c)In Japan, when people take leave of a friend, it is customary to give a bow.
Could we say (a)=(b)=(c)?

I usually see this sentence pattern
“ When V-ing…., I/you/she/he/they/people/…+Verb+…,” but I seldom see this one “When V-ing……, it is adj to…….” Is it alright if we use the second sentence pattern? Could you please help me figure it out?

[hector51]

(b)In Japan, when people taking leave of a friend, it is customary to give a bow.

I think this sentence is wrong!so we can't say these 3 sentences above are the same (I'm not sure,correct me if I'm wrong)

my 2 cents

[Casiopea]

Welcome, Aieda Chiang.

Sentences (a) is correct. Note, though, that "bow" can also function as a verb:

(a) In Japan, when taking leave of a friend, it is customary to (give a) bow.

"to give a bow" is OK, but "bow" works better. It's more efficient.

"when taking leave of a friend" functions adverbially:

EX: In Japan, it is customary to bow when taking leave of a friend.
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Sentence (c) is awkward. Try,

(c) In Japan, when people take leave of a friend, it is customary for them to give a bow.

"when people take leave of a friend" functions adverbially,

EX: In Japan, it is customary for people to bow when they take leave of a friend.

Move the adverbial phrase to the end of the sentence and the noun "people" is replaced by the pronoun "they".
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Sentence (b) is incorrect (*). There's no verb here:

(b) *In Japan, when people taking leave of a friend, it is customary to give a bow.

"taking" is a participle, not a verb. It participates in the verb, like this,

present continuous
am taking
is taking
are taking
was taking
were taking
etc.