Bla bla

\(\begin{cases}\begin{cases}\begin{cases}\left[\begin{array}{l}\left[\begin{array}{l}\left[\begin{array}{l}\int\forall\sqrt{\overrightarrow{\ni\left\vert\larr\overline{\ni\larr\left\Vert\rarr\exponentialE\overrightarrow{\lrArr\vert\cdot\left\Vert\exponentialE\iint\sum_{\placeholder{}}^{\int_{\placeholder{}}^{\int_0^{\infty}\!\int_{\placeholder{}}^{\iiint\int_{\placeholder{}}^{\iint\oint\int_{\placeholder{}}^{\sum_{\placeholder{}}^{\dfrac{\mathrm{d}}{\mathrm{d} x}\sum_{\placeholder{}}^{\prod_{\placeholder{}}^{\dfrac{\mathrm{d}}{\mathrm{d} x}\sum_{\placeholder{}}^{\iint\overgroup{\overrightarrow{\underrightarrow{\min_{\max_{\lim_{x\to\infty}\log\log\ln\ln\lim_{\lim_{\lim_{\tanh\cosh\sinh\cot\tan\cos\sin+=-*\frac{\frac{\frac{7*8.0000000000053Toans}{\placeholder{}}}{\placeholder{}}}{\placeholder{}}}}}}}\hat{\overline{\frac{\overset{\placeholder{}}{\overset{\placeholder{}}{|_{\placeholder{}}^{\underset{\text{\placeholder{}}}{\overset{\text{\placeholder{}}}{\xrightarrow{}}}}_{\placeholder{}}^{\placeholder{}}}}}{\placeholder{}}}}}}}\sum_{\placeholder{}}^{\placeholder{}}}}}}}}}\,\mathrm{d}x}}\right\Vert}\right\Vert}\right\vert}}\\ \placeholder{}\\ \placeholder{}\\ \placeholder{}\end{array}\right.\\ \placeholder{}\\ \placeholder{}\end{array}\right.\\ \placeholder{}\end{array}\right.\\ \placeholder{}\end{cases}\\ \placeholder{}\\ \placeholder{}\end{cases}\\ \placeholder{}\\ \placeholder{}\\ \placeholder{}\end{cases}\)

a. Mùa hè, thời tiết rất nóng.

b. Mặt trời tròn như một quả bóng.