Alli esta is grammatically correct. It is correct because alli esta means "there is" and in your example, There is the first floor, sounds better. The first floor is there doesn't sound correct to me. Hope this helps.
1) a. Llamará
B. Comprenderán
c.iré
D.Serán
E. Venderá
F. Descubriremos
G. Pedirá
H. Asistirás
I. Comenzará
J. Construiremos
Answer: yes is correct
Explanation: because the sentence is offering correct spelling and correct puntuation.
