Question

there are often many people(lying) on the beach.

Answer 1

there
are
often
many
people
(lying)
on
the
beach
这里的lying是动词“lie躺”的现在分词，表示正躺着的意思。（注意，许多以ie结尾的动词的现在分词与动名词是把原动词中的ie改为y再加ing，比如die死这个动词也是这样。）
全句的意思是：常常有一些人躺在海滩上。