It's unnecessary and I suggest to omit the 'on.'
call upon
1. To order; require: I call upon you to tell the truth.
2. To make a demand or a series of demands on: Social institutions are now...
Type: Posts; User: 14Russian; Keyword(s):
It's unnecessary and I suggest to omit the 'on.'
call upon
1. To order; require: I call upon you to tell the truth.
2. To make a demand or a series of demands on: Social institutions are now...
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