Hello, Elle!
It did Lexi no harm!
She is joint leader, for now, anyway.
A tricky puzzle today!
1a a reserve can be a sub(stitute) in a football team, say.
There are things called qua(d) bikes, Elle.
Giving "sub a qua"
Probably underwater sports, I think?
3, if you survive a heat (in a track race, say) you "qualify" (for the final)
So, it is "qualifies".
I am not too sure about the weakens bit, but I can just about see it.
An argument with a qualifying part could possibly weaken the argument?
Not with the setter on that one!
You are correct with attain.
Ta both ways. To the right, and to the left. At + ta + in.
OK?