At least some of the material must have retained the signal unaffected by subsequent changes in the environment.
至少有一些材料肯定保留了不受后续环境变化影响的信号。
2
Stone statues were worked from single rectangular blocks of material and retained the compactness of the original shape.
石像是由单个长方形块状材料制成的，并保持原有形状的坚实度。
3
Some (like the Whittalls) retained British nationality over generations of Ottoman life, and it is their English-language diaries, letters and documents that provide Mr Milton with his best material.