白细胞____细胞核，比红细胞____，但数量少。当病菌侵入人体内时，能穿过毛细血管，集中到病菌入侵部位，将病菌包围、吞噬。

根据句意、释义或中文提示,写出句中所缺单词，使句子通顺。
（1）His parents are angry at his school work. They can't see his ____  (进步)after each exam.
（2）I don't know ____  ( if ) I will have time to join in some activities at school.
（3）Sometimes, I want to ____  (say that you will not do something) to do so much homework.
（4）Orange and yellow are warm colours, they can give you a happy and ____ (满意的) feeling.
（5）Peter is doing an ____  in the laboratory now.

小燕学习地理时，发现同纬度的华北平原、黄土高原、塔里木盆地自然景观差异很大．她收集的三地景观图片如下，请你根据相关图片及所学的地理知识回答问题