diff --git a/zhang1_chang2_yu4/.keep b/zhang1_chang2_yu4/.keep
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/zhang1_chang2_yu4/hw1/.keep b/zhang1_chang2_yu4/hw1/.keep
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/zhang1_chang2_yu4/hw1/hw1.png b/zhang1_chang2_yu4/hw1/hw1.png
new file mode 100644
index 0000000000000000000000000000000000000000..779ab735151b28e7317720cc07779d722f84d18a
Binary files /dev/null and b/zhang1_chang2_yu4/hw1/hw1.png differ
diff --git a/zhang1_chang2_yu4/hw2/.keep b/zhang1_chang2_yu4/hw2/.keep
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/zhang1_chang2_yu4/hw2/hw2.2.png b/zhang1_chang2_yu4/hw2/hw2.2.png
new file mode 100644
index 0000000000000000000000000000000000000000..be42aa8cfe851e0d2e72153d5389c41b1edc7df2
Binary files /dev/null and b/zhang1_chang2_yu4/hw2/hw2.2.png differ
diff --git a/zhang1_chang2_yu4/hw2/hw2.png b/zhang1_chang2_yu4/hw2/hw2.png
new file mode 100644
index 0000000000000000000000000000000000000000..4387611dac2238e3b184c1ad73b2a71b93eec302
Binary files /dev/null and b/zhang1_chang2_yu4/hw2/hw2.png differ
diff --git a/zhang1_chang2_yu4/hw3/.keep b/zhang1_chang2_yu4/hw3/.keep
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/zhang1_chang2_yu4/hw3/hw3.png b/zhang1_chang2_yu4/hw3/hw3.png
new file mode 100644
index 0000000000000000000000000000000000000000..cfdb85a95e4c7d471189cf114351a3fc5db5d098
Binary files /dev/null and b/zhang1_chang2_yu4/hw3/hw3.png differ