Answer:
1.The first one is because the British army fight placed in the frontline head on against the Germans.
But the majority of loss of life can be attributed to famine and disease – horrific conditions meant fevers, parasites and infections were rife on the frontline and ripped through the troops in the trenches. Among the diseases and viruses that were most prevalent were influenza, typhoid, trench foot and trench fever
2.First of all they send war supply for the British and the French, known as Lend Lease. In lend lease the British and the French can pay for the material they bought after the war.
3.During the first 2 ½ years of combat, the U.S. was a neutral party and the economic boom came primarily from exports. The total value of U.S. exports grew from $2.4 billion in 1913 to $6.2 billion in 1917.