adjective
1
BAD : I would be glad if you could send me an application form.
GOOD : I would be grateful if you could send me an application form.
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To make a formal request, use would be grateful if (NOT glad ): 'We would be grateful if you could consider this matter at your earliest convenience.'
2
BAD : She was a very glad person, and very intelligent.
GOOD : She was a very happy person, and very intelligent.
BAD : We hope that you will like this school and be glad here.
GOOD : We hope that you will like this school and be happy here.
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glad (not used in front of a noun) = pleased and happy about something in particular: 'I'm so glad your wife is feeling better.' 'I'm glad it wasn't my turn to pay.'
happy = enjoying life: 'She's a lot happier now that the examinations are over.'