Q1.
Try speaking the following lines. Start slow and gradually increase your speed. See how many times you can say each one without stopping or making a mistake.
a. Red lorry blue lorry.
Answer
Say it like this: Red · lor–ry · blue · lor–ry. Say it four times slowly, then four times a little faster, then as fast as you can.
What it is training: the two sounds r and l. Your tongue does different things for them. For r the tongue curls back and touches nothing. For l the tip of the tongue touches the ridge just behind your top front teeth. The words red and lorry make you swap between the two, again and again.
Tip: Do not speed up until you can say it four times without a slip. Speed comes from being sure, not from hurrying. A lorry is a truck.