4. Such is this boy's intelligence , he can solve all problems in no time 

5. Only when you identity has been led , will you be allowed in 

6.  So important is the problem that everybody is concerned of it 

* Lý thuyết : 

- so + adj + that .... --> Đảo ngữ : So + adj + be + S that ... 

- such + (a/ an ) + adj + N that ... --> Đảo ngữ : Such + be + N  that ... 

- Only when + S + V , inversion : Chỉ cho đến khi , ... 

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4. This boy is intelligent. He can solve all the problems in no time.

$\Rightarrow$ Such an intelligent boy is he that he can solve all the problems in no time.

- Cấu trúc đảo ngữ với "Such that":

$\bullet$ $\rm \text{Such (+ a/an)  + adj. + N + to be (chia thì) + that + clause}$

$\bullet$ $\rm \text{Such + to be (chia thì) (+ a/an) + adj. + N + that + clause}$

6. It is such an important problem that everybody is concerned of it.

$\Rightarrow$ So important is the problem that everybody is concerned of it.

- Cấu trúc đảo ngữ với "So that":

$\bullet$ $\rm \text{So + adj. + to be (chia thì) + S + that + clause}$

$\bullet$ $\rm \text{So + adv. + trợ động từ + S + $V_0$ + that + clause}$