It is irony. Normally, when someone is unusually prompt, they are early. However, the speaker is using irony to say that her doctor is always late.
The correct subordinating conjunction is "yet" and the sentence is completed as follows:
Mandy practiced karate every day, yet she failed to beat her final opponent.
The word "yet" is a subordinating conjunction that means "nevertheless" or "however", it is associated with negative statements in order to mention that an event did not take place.
In this sentence, it explains that even though Mandy had practiced she did not beat her opponent.
In sonnet 130, the narrator compares his loved one to natural elements presenting them as less worth, but ultimately prettier to him.<span />
HE CHEATED ON HIMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
