Hello

Question

Please if you can help me out to understand where to put de+infinitive. I am so confused. 
Par example- laissez-moi de penser pourquoi de ici ? 
C’est mon rêve de travailler à l’étranger. Why I putted de here I can simply write c’est mon rêve travailler.
Et je sais que je dois pratiquer. Why here it’s not de after pratiquer? 
Please if you can share me the lesson of this I have tried to search a lot but I am not able to understand properly where to put de+infinitive and where not.
Thank You :)

Answer

Hi Shruti,
the use of prepositions in French is not straightforward or intuitive. There is no simple rule to follow which would tell you unambiguously which presposition to use. At least, I am not aware of one.
Je laisse mes lunettes à la maison -- I leave my glasses at home.Laisse du gâteau à ton frère. -- Leave some cake for your brother.
I haven't encountered laisser de very often, except maybe in:
Cela ne laisse pas de surprendre. -- That never ceases to surprise.
And by extrapolation, here is my explanation for laisser de penser.
Laisse-moi de penser. -- Leave me to think.Laisse-moi penser. -- Let me think.
The input of a native speaker would be appreciated.
-- Chris (not a native speaker).