Some Type A and style comments:

Abstract: 
- Type-II → type-II
- 350-470 GeV and 350-550 GeV → use double-dash for the range
-top quark couplings of lighter new particles. → top quark couplings to lighter new particles.

Introduction:
L7: Remove “due to small SM cross section”. It sounds like BSM affects 4top process because ots rate is small in SM! Reads weird. 
L9: Type → type
L20: do we really need reference [24] for the W decay?!
L20: why u, d, c, s in brackets? It sounds like by quark we always mean these four. This is repeated in L21.
Suggest to change:
L20: leptons or (u, d, c, s) quarks → leptons or light (u, d, c, s) quarks  
L21: the hadronization of (u, d, c, s) quarks → the hadronization of light quarks
L25,26: the sentence is unnecessarily long and does not read well. Suggest to change:
Because of low level of backgrounds these channels are the most sensitive to the SM tt tt process.

L26: remove the reference 25 here
L27: Add reference 25 to CMS references here
L36-39: A super long sentence. Break into 2-3 pieces.
Table 2: change all single dashes to double dash
Fig1. 2 and 3: put all processes with contribution below 10% into one  entry as others. The plots are difficult to read