The phrase "and cannot be better" is correct and usable in written English.
It can be used to express that something is at its best possible state or cannot be improved upon.
Example: "This dish is perfect as it is, and cannot be better."
Alternatives: "and could not be improved" or "and is as good as it gets."
Thus, (text{R}(boldsymbol{M}boldsymbol{y};0)>text{R}(boldsymbol{C}boldsymbol{y};0)) and My cannot be better than Cy.
From this study, the following results are obtained: (1) the impact force time history, maximum displacement at the loading point and crack patterns caused in the side-surface of the arch beams can be simulated, which are in good agreement with the experimental results; however, (2) the damped free response after unloading and residual displacement cannot be better simulated.
In The Scientific Image (1980), van Fraassen uses a now-classic example to illustrate the possibility that even our best scientific theories might have empirical equivalents: that is, alternative theories making the very same empirical predictions, and which therefore cannot be better or worse supported by any possible body of evidence.
T. S. Eliot's tenet of a necessary separation of "the man who suffers and the mind which creates" cannot be better exemplified than by Arbus at that recurrent moment when we as viewers are abandoned to visions overwhelmingly both fierce and tender.
To Arnauld, he writes the following: "I hold that philosophy cannot be better reestablished and reduced to something precise, than by recognizing only substances or complete beings endowed with a true unity, together with the different states that succeed one another; everything else is only phenomena, abstractions, or relations".
And don't assume unrelated fathers cannot be better fathers than the biological father you're seeking, especially since they have been a part of your mother's life.
It passes understanding why Blair and Brown have put such useless people in charge of it; but the thought that they cannot be better advised is worrying.
"Things cannot be better than finishing first for my last Friday," enthused Alesi who will be driving in his 201st grand prix.
