Step 1: Understanding the components of a plough.
A plough typically consists of a common main frame, disc beam assemblies, and a gauge wheel. A heavy spring-loaded furrow wheel may be an additional feature but is not always part of the plough.
Step 2: Analysis of options.
- (A) Common main frame: Correct. This is a fundamental component of the plough.
- (B) Disc beam assemblies: Correct. These are used in ploughs to cut and turn the soil.
- (C) Heavy spring-loaded furrow wheel: Incorrect. While this wheel is important for some ploughs, it is not essential in all ploughs.
- (D) Gauge wheel: Correct. This controls the depth of the plough during operation.
Step 3: Conclusion.
Thus, the correct answer is (A), (B) and (D) only.
Final Answer:
\[
\boxed{1. (A), (B) and (D) only}
\]